通常，在编码时，我们必须处理其中包含数十个字段的一些POJO对象。 很多时候，我们通过一个带有数十个参数的构造函数来初始化这些类，这以任何可能的想象的方式都是可怕的。 除此之外，使用这些构造函数的函数几乎不可测试。 让我们仔细研究一下使用Builder来改变这种情况，以及Hamcrest匹配器和Guava Predicates对它进行单元测试。 让我们开始看一下POJO类。

SomeBigPojo.java

package pl.grzejszczak.marcin.junit.matchers.pojo;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 21:05*/
public class SomeBigPojo {private String stringField0;private Integer integerField0;private Boolean booleanField0;private String stringField1;private Integer integerField1;private Boolean booleanField1;private String stringField2;private Integer integerField2;private Boolean booleanField2;private String stringField3;private Integer integerField3;private Boolean booleanField3;private String stringField4;private Integer integerField4;private Boolean booleanField4;private String stringField5;private Integer integerField5;private Boolean booleanField5;private String stringField6;private Integer integerField6;private Boolean booleanField6;private String stringField7;private String stringField8;private String stringField9;public SomeBigPojo(String stringField0, Integer integerField0, Boolean booleanField0, String stringField1, Integer integerField1, Boolean booleanField1, String stringField2, Integer integerField2, Boolean booleanField2, String stringField3, Integer integerField3, Boolean booleanField3, String stringField4, Integer integerField4, Boolean booleanField4, String stringField5, Integer integerField5, Boolean booleanField5, String stringField6, Integer integerField6, Boolean booleanField6, String stringField7, String stringField8, String stringField9) {this.stringField0 = stringField0;this.integerField0 = integerField0;this.booleanField0 = booleanField0;this.stringField1 = stringField1;this.integerField1 = integerField1;this.booleanField1 = booleanField1;this.stringField2 = stringField2;this.integerField2 = integerField2;this.booleanField2 = booleanField2;this.stringField3 = stringField3;this.integerField3 = integerField3;this.booleanField3 = booleanField3;this.stringField4 = stringField4;this.integerField4 = integerField4;this.booleanField4 = booleanField4;this.stringField5 = stringField5;this.integerField5 = integerField5;this.booleanField5 = booleanField5;this.stringField6 = stringField6;this.integerField6 = integerField6;this.booleanField6 = booleanField6;this.stringField7 = stringField7;this.stringField8 = stringField8;this.stringField9 = stringField9;}public String getStringField0() {return stringField0;}public void setStringField0(String stringField0) {this.stringField0 = stringField0;}public Integer getIntegerField0() {return integerField0;}public void setIntegerField0(Integer integerField0) {this.integerField0 = integerField0;}public Boolean getBooleanField0() {return booleanField0;}public void setBooleanField0(Boolean booleanField0) {this.booleanField0 = booleanField0;}public String getStringField1() {return stringField1;}public void setStringField1(String stringField1) {this.stringField1 = stringField1;}public Integer getIntegerField1() {return integerField1;}public void setIntegerField1(Integer integerField1) {this.integerField1 = integerField1;}public Boolean getBooleanField1() {return booleanField1;}public void setBooleanField1(Boolean booleanField1) {this.booleanField1 = booleanField1;}public String getStringField2() {return stringField2;}public void setStringField2(String stringField2) {this.stringField2 = stringField2;}public Integer getIntegerField2() {return integerField2;}public void setIntegerField2(Integer integerField2) {this.integerField2 = integerField2;}public Boolean getBooleanField2() {return booleanField2;}public void setBooleanField2(Boolean booleanField2) {this.booleanField2 = booleanField2;}public String getStringField3() {return stringField3;}public void setStringField3(String stringField3) {this.stringField3 = stringField3;}public Integer getIntegerField3() {return integerField3;}public void setIntegerField3(Integer integerField3) {this.integerField3 = integerField3;}public Boolean getBooleanField3() {return booleanField3;}public void setBooleanField3(Boolean booleanField3) {this.booleanField3 = booleanField3;}public String getStringField4() {return stringField4;}public void setStringField4(String stringField4) {this.stringField4 = stringField4;}public Integer getIntegerField4() {return integerField4;}public void setIntegerField4(Integer integerField4) {this.integerField4 = integerField4;}public Boolean getBooleanField4() {return booleanField4;}public void setBooleanField4(Boolean booleanField4) {this.booleanField4 = booleanField4;}public String getStringField5() {return stringField5;}public void setStringField5(String stringField5) {this.stringField5 = stringField5;}public Integer getIntegerField5() {return integerField5;}public void setIntegerField5(Integer integerField5) {this.integerField5 = integerField5;}public Boolean getBooleanField5() {return booleanField5;}public void setBooleanField5(Boolean booleanField5) {this.booleanField5 = booleanField5;}public String getStringField6() {return stringField6;}public void setStringField6(String stringField6) {this.stringField6 = stringField6;}public Integer getIntegerField6() {return integerField6;}public void setIntegerField6(Integer integerField6) {this.integerField6 = integerField6;}public Boolean getBooleanField6() {return booleanField6;}public void setBooleanField6(Boolean booleanField6) {this.booleanField6 = booleanField6;}public String getStringField7() {return stringField7;}public void setStringField7(String stringField7) {this.stringField7 = stringField7;}public String getStringField8() {return stringField8;}public void setStringField8(String stringField8) {this.stringField8 = stringField8;}public String getStringField9() {return stringField9;}public void setStringField9(String stringField9) {this.stringField9 = stringField9;}@Overridepublic String toString() {final StringBuilder sb = new StringBuilder();sb.append("SomeBigPojo");sb.append("{stringField0='").append(stringField0).append('\'');sb.append(", integerField0=").append(integerField0);sb.append(", booleanField0=").append(booleanField0);sb.append(", stringField1='").append(stringField1).append('\'');sb.append(", integerField1=").append(integerField1);sb.append(", booleanField1=").append(booleanField1);sb.append(", stringField2='").append(stringField2).append('\'');sb.append(", integerField2=").append(integerField2);sb.append(", booleanField2=").append(booleanField2);sb.append(", stringField3='").append(stringField3).append('\'');sb.append(", integerField3=").append(integerField3);sb.append(", booleanField3=").append(booleanField3);sb.append(", stringField4='").append(stringField4).append('\'');sb.append(", integerField4=").append(integerField4);sb.append(", booleanField4=").append(booleanField4);sb.append(", stringField5='").append(stringField5).append('\'');sb.append(", integerField5=").append(integerField5);sb.append(", booleanField5=").append(booleanField5);sb.append(", stringField6='").append(stringField6).append('\'');sb.append(", integerField6=").append(integerField6);sb.append(", booleanField6=").append(booleanField6);sb.append(", stringField7='").append(stringField7).append('\'');sb.append(", stringField8='").append(stringField8).append('\'');sb.append(", stringField9='").append(stringField9).append('\'');sb.append('}');return sb.toString();}
}

现在看一下为了摆脱庞大构造函数的使用而使用的builder类。 而且，您可以设置任何所需的内容，而无需为不需要的字段输入null。

SomeBigPojoBuilder.java

package pl.grzejszczak.marcin.junit.matchers.builder;import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static com.google.common.base.Preconditions.checkNotNull;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 21:08*/
public class SomeBigPojoBuilder {/** A field with some default value */private String stringField0 = "defaultValueForString0";/** A field with some default value */private Integer integerField0 = 100;/** A field with some default value */private Boolean booleanField0 = true;private String stringField1;private Integer integerField1;private Boolean booleanField1;private String stringField2;private Integer integerField2;private Boolean booleanField2;private String stringField3;private Integer integerField3;private Boolean booleanField3;private String stringField4;private Integer integerField4;private Boolean booleanField4;private String stringField5;private Integer integerField5;private Boolean booleanField5;private String stringField6;private Integer integerField6;private Boolean booleanField6;private String stringField7;private String stringField8;private String stringField9;public SomeBigPojoBuilder setStringField0(String stringField0) {this.stringField0 = stringField0;return this;}public SomeBigPojoBuilder setIntegerField0(Integer integerField0) {this.integerField0 = integerField0;return this;}public SomeBigPojoBuilder setBooleanField0(Boolean booleanField0) {this.booleanField0 = booleanField0;return this;}public SomeBigPojoBuilder setStringField1(String stringField1) {this.stringField1 = stringField1;return this;}public SomeBigPojoBuilder setIntegerField1(Integer integerField1) {this.integerField1 = integerField1;return this;}public SomeBigPojoBuilder setBooleanField1(Boolean booleanField1) {this.booleanField1 = booleanField1;return this;}public SomeBigPojoBuilder setStringField2(String stringField2) {this.stringField2 = stringField2;return this;}public SomeBigPojoBuilder setIntegerField2(Integer integerField2) {this.integerField2 = integerField2;return this;}public SomeBigPojoBuilder setBooleanField2(Boolean booleanField2) {this.booleanField2 = booleanField2;return this;}public SomeBigPojoBuilder setStringField3(String stringField3) {this.stringField3 = stringField3;return this;}public SomeBigPojoBuilder setIntegerField3(Integer integerField3) {this.integerField3 = integerField3;return this;}public SomeBigPojoBuilder setBooleanField3(Boolean booleanField3) {this.booleanField3 = booleanField3;return this;}public SomeBigPojoBuilder setStringField4(String stringField4) {this.stringField4 = stringField4;return this;}public SomeBigPojoBuilder setIntegerField4(Integer integerField4) {this.integerField4 = integerField4;return this;}public SomeBigPojoBuilder setBooleanField4(Boolean booleanField4) {this.booleanField4 = booleanField4;return this;}public SomeBigPojoBuilder setStringField5(String stringField5) {this.stringField5 = stringField5;return this;}public SomeBigPojoBuilder setIntegerField5(Integer integerField5) {this.integerField5 = integerField5;return this;}public SomeBigPojoBuilder setBooleanField5(Boolean booleanField5) {this.booleanField5 = booleanField5;return this;}public SomeBigPojoBuilder setStringField6(String stringField6) {this.stringField6 = stringField6;return this;}public SomeBigPojoBuilder setIntegerField6(Integer integerField6) {this.integerField6 = integerField6;return this;}public SomeBigPojoBuilder setBooleanField6(Boolean booleanField6) {this.booleanField6 = booleanField6;return this;}public SomeBigPojoBuilder setStringField7(String stringField7) {this.stringField7 = stringField7;return this;}public SomeBigPojoBuilder setStringField8(String stringField8) {this.stringField8 = stringField8;return this;}public SomeBigPojoBuilder setStringField9(String stringField9) {this.stringField9 = stringField9;return this;}/*** Some function checking the state of our POJO*/private void checkState(){checkNotNull(stringField1, "StringField1 must not be null!");}public SomeBigPojo createSomeBigPojoWithBuilder() {checkState();return new SomeBigPojo(stringField0, integerField0, booleanField0, stringField1, integerField1, booleanField1, stringField2, integerField2, booleanField2, stringField3, integerField3, booleanField3, stringField4, integerField4, booleanField4, stringField5, integerField5, booleanField5, stringField6, integerField6, booleanField6, stringField7, stringField8, stringField9);}
}

看一下checkState函数，该函数验证对象是否处于所需状态。 这样，如果某些条件不完整，我们可能不允许创建对象。 对于这种情况，我们使用番石榴的谓词– checkNotNull方法。

请注意，Builder模式背后的概念是将对象的创建委托给Builder。 实际上，在纯Builder设计模式实现中，我们将必须具有Director，对Builder的一些抽象以及这样的Builder的具体实现。 在我们的例子中，我们简化了这种模式–我使用了IntelliJ的重构选项。 要使它看起来更好，可以做的是从POJO中删除构造函数，并仅通过setter传递值（这实际上是我在我的一个项目中所做的事情）。 现在让我们看一些用法示例：

SomeServiceImpl.java

package pl.grzejszczak.marcin.junit.matchers.service;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import pl.grzejszczak.marcin.junit.matchers.builder.SomeBigPojoBuilder;
import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static java.lang.String.format;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 21:25*/
public class SomeServiceImpl implements SomeService {private static final Logger LOGGER = LoggerFactory.getLogger(SomeServiceImpl.class);/** Could be an abstraction of builders injected by a setter - possible to mock */private SomeBigPojoBuilder someBigPojoBuilder;/*** Hard to unit test*/@Overridepublic void someLogicForAPojoWithoutBuilder() {LOGGER.debug("SomeLogicForAPojoWithoutBuilder executed");SomeBigPojo someBigPojo = new SomeBigPojo("string", 1, false, "other string", 123, true, "something else", 321, false, "yet another string", 111, true, "something", 2, false, "More", 3, true, "String", 12, false, "some", "value", "ofString");// Any chance of knowing what is the value of stringField8 basing on the constructor?LOGGER.debug(format("StringField8 is equal [%s]%n", someBigPojo.getStringField8()));// Print the objectLOGGER.debug(someBigPojo.toString());}@Overridepublic void someLogicForAPojoWithBuilder() {LOGGER.debug("SomeLogicForAPojoWithBuilder executed");SomeBigPojo someBigPojo = someBigPojoBuilder.setStringField0("string").setIntegerField0(1).setBooleanField0(false).setStringField1("other string").setIntegerField1(123).setBooleanField1(true).setStringField2("something else").setIntegerField2(321).setBooleanField2(false).setStringField3("yet another string").setIntegerField3(111).setBooleanField3(false).setStringField4("something").setIntegerField4(2).setBooleanField4(false).setStringField5("More").setIntegerField5(3).setBooleanField5(true).setStringField6("String").setIntegerField6(12).setBooleanField6(false).setStringField7("some").setStringField8("value").setStringField9("ofString").createSomeBigPojoWithBuilder();// Looking at the builder now I guess it's obvious what the value of StringField8LOGGER.debug(format("StringField8 is equal [%s]%n", someBigPojo.getStringField8()));// Print the objectLOGGER.debug(someBigPojo.toString());}@Overridepublic void someLogicForAPojoWithBuilderBadArgument() {LOGGER.debug("someLogicForAPojoWithBuilderBadArgument executed");SomeBigPojo someBigPojo = someBigPojoBuilder.setStringField0("string").setIntegerField0(1).setBooleanField0(true).setIntegerField1(123).setBooleanField1(true).setStringField2("something else").setIntegerField2(321).setBooleanField2(false).setStringField3("yet another string").setIntegerField3(111).setBooleanField3(false).setStringField4("something").setIntegerField4(2).setBooleanField4(false).setStringField5("More").setIntegerField5(3).setBooleanField5(true).setStringField6("String").setIntegerField6(12).setBooleanField6(false).setStringField7("some").setStringField8("value").setStringField9("ofString").createSomeBigPojoWithBuilder();// Print the object - will we even see an outputLOGGER.debug(someBigPojo.toString());}public void setSomeBigPojoBuilder(SomeBigPojoBuilder someBigPojoBuilder) {this.someBigPojoBuilder = someBigPojoBuilder;}
}

请注意，现在创建对象非常清楚，定义一个字段是否已设置也很容易。

让我们继续进行Hamcrest匹配器，这将帮助我们对班级进行单元测试。 我不会尝试完成100％的完整代码覆盖-这篇文章的目的是说明Hamcrest Matchers如何成为您的单元测试的补充。 通常单元测试还不清楚，看起来像这样：

SomeBigPojoBuilderNoMatchersAndNoRefactoringTest.java

package pl.grzejszczak.marcin.junit.matchers.builder;import org.junit.Before;
import org.junit.Test;
import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static junit.framework.Assert.assertTrue;
import static org.apache.commons.lang.StringUtils.isNumeric;
import static pl.grzejszczak.marcin.junit.matchers.pojo.SomePojoConstants.*;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 23:02*/
public class SomeBigPojoBuilderNoMatchersAndNoRefactoringTest {private SomeBigPojoBuilder objectUnderTest;@Beforepublic void setUp() {objectUnderTest = new SomeBigPojoBuilder();}@Testpublic void testCreateSomeBigPojoWithBuilder() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setBooleanField1(true).setStringField0("1").setStringField1("12").setStringField2("123").setStringField3("1234").setStringField4("12345").setStringField5("123456").setStringField6("1234567").setStringField7("12345678").setStringField8("123456789").setStringField9("1234567890").createSomeBigPojoWithBuilder();isPojoProperlyBuilt(someBigPojo);}@Test(expected = AssertionError.class)public void testCreateSomeBigPojoWithBuilderWrongFields() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setStringField0("0").setStringField1("Too long").createSomeBigPojoWithBuilder();isPojoProperlyBuilt(someBigPojo);}private void isPojoProperlyBuilt(SomeBigPojo someBigPojo) {assertTrue(someBigPojo.getStringField0().length() == STRING_FIELD_0_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField1().length() == STRING_FIELD_1_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField2().length() == STRING_FIELD_2_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField3().length() == STRING_FIELD_3_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField4().length() == STRING_FIELD_4_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField5().length() == STRING_FIELD_5_LENGTH);assertTrue(someBigPojo.getStringField6().length() == STRING_FIELD_6_LENGTH);assertTrue(someBigPojo.getStringField7().length() == STRING_FIELD_7_LENGTH);assertTrue(someBigPojo.getStringField8().length() == STRING_FIELD_8_LENGTH);assertTrue(someBigPojo.getStringField9().length() == STRING_FIELD_9_LENGTH);}
}

简单的重构可以使它们看起来更好……

SomeBigPojoBuilderNoMatchersTest.java

package pl.grzejszczak.marcin.junit.matchers.builder;import org.junit.Before;
import org.junit.Test;
import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static junit.framework.Assert.assertNotNull;
import static junit.framework.Assert.assertTrue;
import static org.apache.commons.lang.StringUtils.isNumeric;
import static pl.grzejszczak.marcin.junit.matchers.pojo.SomePojoConstants.*;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 23:02*/
public class SomeBigPojoBuilderNoMatchersTest {private SomeBigPojoBuilder objectUnderTest;@Beforepublic void setUp() {objectUnderTest = new SomeBigPojoBuilder();}@Testpublic void testCreateSomeBigPojoWithBuilder() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setBooleanField1(true).setStringField0("1").setStringField1("12").setStringField2("123").setStringField3("1234").setStringField4("12345").setStringField5("123456").setStringField6("1234567").setStringField7("12345678").setStringField8("123456789").setStringField9("1234567890").createSomeBigPojoWithBuilder();isPojoProperlyBuilt(someBigPojo);}@Test(expected = AssertionError.class)public void testCreateSomeBigPojoWithBuilderWrongFields() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setStringField0("0").setStringField1("too long").createSomeBigPojoWithBuilder();isPojoProperlyBuilt(someBigPojo);}private void isPojoProperlyBuilt(SomeBigPojo someBigPojo) {isOfGivenLength(someBigPojo.getStringField0(), STRING_FIELD_0_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField1(), STRING_FIELD_1_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField2(), STRING_FIELD_2_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField3(), STRING_FIELD_3_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField4(), STRING_FIELD_4_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField5(), STRING_FIELD_5_LENGTH);isOfGivenLength(someBigPojo.getStringField6(), STRING_FIELD_6_LENGTH);isOfGivenLength(someBigPojo.getStringField7(), STRING_FIELD_7_LENGTH);isOfGivenLength(someBigPojo.getStringField8(), STRING_FIELD_8_LENGTH);isOfGivenLength(someBigPojo.getStringField9(), STRING_FIELD_9_LENGTH);}private void isOfGivenLength(String pojo, final Integer expectedLength) {assertNotNull(pojo);assertTrue(expectedLength == pojo.length());}private void isFieldOfNumericValue(String field) {assertTrue(isNumeric(field));}
}

看起来不错，不是吗？ 以及使用Matchers代替函数呢？

SomeBigPojoBuilderTest.kava

package pl.grzejszczak.marcin.junit.matchers.builder;import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.junit.Before;
import org.junit.Test;
import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static java.lang.String.format;
import static junit.framework.Assert.assertTrue;
import static org.apache.commons.lang.StringUtils.isNumeric;
import static org.junit.Assert.assertThat;
import static pl.grzejszczak.marcin.junit.matchers.pojo.SomePojoConstants.*;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 23:02*/
public class SomeBigPojoBuilderTest {private SomeBigPojoBuilder objectUnderTest;@Beforepublic void setUp(){objectUnderTest = new SomeBigPojoBuilder();}@Testpublic void testCreateSomeBigPojoWithBuilder() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setBooleanField1(true).setStringField0("1").setStringField1("12").setStringField2("123").setStringField3("1234").setStringField4("12345").setStringField5("123456").setStringField6("1234567").setStringField7("12345678").setStringField8("123456789").setStringField9("1234567890").createSomeBigPojoWithBuilder();assertThat(someBigPojo, isPojoProperlyBuilt());}@Test(expected = AssertionError.class)public void testCreateSomeBigPojoWithBuilderWrongFields() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setStringField0("0").setStringField1("Too long").createSomeBigPojoWithBuilder();assertThat(someBigPojo, isPojoProperlyBuilt());}/*** Let us assume that there is a specific business case that we have to take into consideration regarding some particular field** @return*/private static Matcher isPojoProperlyBuilt() {return new BaseMatcher() {@Overridepublic boolean matches(Object o) {assertTrue(o instanceof SomeBigPojo);SomeBigPojo someBigPojo = (SomeBigPojo) o;assertThat(someBigPojo.getStringField0(), isOfGivenLength(STRING_FIELD_0_LENGTH));assertThat(someBigPojo.getStringField0(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField1(), isOfGivenLength(STRING_FIELD_1_LENGTH));assertThat(someBigPojo.getStringField1(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField2(), isOfGivenLength(STRING_FIELD_2_LENGTH));assertThat(someBigPojo.getStringField2(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField3(), isOfGivenLength(STRING_FIELD_3_LENGTH));assertThat(someBigPojo.getStringField3(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField4(), isOfGivenLength(STRING_FIELD_4_LENGTH));assertThat(someBigPojo.getStringField4(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField5(), isOfGivenLength(STRING_FIELD_5_LENGTH));assertThat(someBigPojo.getStringField6(), isOfGivenLength(STRING_FIELD_6_LENGTH));assertThat(someBigPojo.getStringField7(), isOfGivenLength(STRING_FIELD_7_LENGTH));assertThat(someBigPojo.getStringField8(), isOfGivenLength(STRING_FIELD_8_LENGTH));assertThat(someBigPojo.getStringField9(), isOfGivenLength(STRING_FIELD_9_LENGTH));return true;}@Overridepublic void describeTo(Description description) {description.appendText("Lengths of fields are limited and the first 4 fields are numeric");}};}private static Matcher isOfGivenLength(final Integer expectedLength) {return new BaseMatcher() {public boolean matches(Object o) {assertTrue(o instanceof String);return expectedLength == String.valueOf(o).length();}public void describeTo(Description description) {description.appendText(format("String's length should be equal to [%d]", expectedLength));}};}private static Matcher isFieldOfNumericValue() {return new BaseMatcher() {public boolean matches(Object o) {assertTrue(o instanceof String);return isNumeric(String.valueOf(o));}public void describeTo(Description description) {description.appendText("The value of the field should be numeric");}};}
}

以下主要方法执行服务的功能：

package pl.grzejszczak.marcin.junit.matchers;import pl.grzejszczak.marcin.junit.matchers.builder.SomeBigPojoBuilder;
import pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 22:38*/
public class MatcherMain {public static void main(String[] args){SomeServiceImpl someService = new SomeServiceImpl();someService.setSomeBigPojoBuilder(new SomeBigPojoBuilder());someService.someLogicForAPojoWithoutBuilder();someService.setSomeBigPojoBuilder(new SomeBigPojoBuilder());someService.someLogicForAPojoWithBuilder();someService.setSomeBigPojoBuilder(new SomeBigPojoBuilder());someService.someLogicForAPojoWithBuilderBadArgument();}
}

日志是：

pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:27 SomeLogicForAPojoWithoutBuilder executed
pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:30 StringField8 is equal [value]pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:32 SomeBigPojo{stringField0='string', integerField0=1, booleanField0=false, stringField1='other string', integerField1=123, booleanField1=true, stringField2='something else', integerField2=321, booleanField2=false, stringField3='yet another string', integerField3=111, booleanField3=true, stringField4='something', integerField4=2, booleanField4=false, stringField5='More', integerField5=3, booleanField5=true, stringField6='String', integerField6=12, booleanField6=false, stringField7='some', stringField8='value', stringField9='ofString'}
pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:37 SomeLogicForAPojoWithBuilder executed
pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:65 StringField8 is equal [value]pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:67 SomeBigPojo{stringField0='string', integerField0=1, booleanField0=false, stringField1='other string', integerField1=123, booleanField1=true, stringField2='something else', integerField2=321, booleanField2=false, stringField3='yet another string', integerField3=111, booleanField3=false, stringField4='something', integerField4=2, booleanField4=false, stringField5='More', integerField5=3, booleanField5=true, stringField6='String', integerField6=12, booleanField6=false, stringField7='some', stringField8='value', stringField9='ofString'}
pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:72 someLogicForAPojoWithBuilderBadArgument executed
Exception in thread "main" java.lang.NullPointerException: StringField1 must not be null!at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:208)at pl.grzejszczak.marcin.junit.matchers.builder.SomeBigPojoBuilder.checkState(SomeBigPojoBuilder.java:166)at pl.grzejszczak.marcin.junit.matchers.builder.SomeBigPojoBuilder.createSomeBigPojoWithBuilder
(SomeBigPojoBuilder.java:170)at pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl.someLogicForAPojoWithBuilderBadArgument
(SomeServiceImpl.java:73)at pl.grzejszczak.marcin.junit.matchers.MatcherMain.main(MatcherMain.java:23)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)at java.lang.reflect.Method.invoke(Method.java:597)at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

在我看来，这看起来确实不错。 那你呢？ 可在此处找到源代码，代码太多。

翻译自: https://www.javacodegeeks.com/2013/04/hamcrest-matchers-guava-predicate-and-builder-design-pattern.html