前言

​ 一直很想知道IDE是如何自动去生成类的构造和getter、setter方法，大概是有个想法，获取当前的类，利用反射去获取属性名和类型，然后生成，所以我想自己试试。

写个模板类

package common;public class Templates {public static final String T_CLASS      = "package {0};\n\n{1}public class {2} {\n\n{3}\n\n{5}\n\n{4}\n}";public static final String T_GET        = "\tpublic {0} get{1} () {\n\t\treturn {2};\n\t}\n";public static final String T_SET        = "\tpublic void set{0}({1} {2}) {\n\t\tthis.{2}={2};\n\t}\n";public static final String T_ATTR1      = "\tprivate {0} {1};\n";public static final String T_ATTR2      = "\t\tthis.{0}={0};\n";public static final String T_IMPORT     = "import java.util.Date;\n\n";public static final String T_CONSTRUCT  = "\tpublic {0}({1}) {\n\t\tsuper();\n{2}\n\t}\n";public static String format(String pattern, String ... arguments){String format = pattern;for(int i=0;i<arguments.length;i++){format = format.replace("{"+i+"}",arguments[i]);}return format;}public static String loadTemplate(String clazz,String pack,String port,String attrs,String get_set,String construct){return format(T_CLASS, clazz,pack,port,attrs,get_set,construct);}
}

创建一个实体类

package cc.vvxtoys.pojo;public class Student {private int id;private String name;private String sex;private String school;}

工具类

package common;import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;import org.apache.log4j.Logger;public class Common {private static Logger log = Logger.getLogger(Common.class);//获得绝对路径public static String absolutePath(String pack, String name, String suffix) {List<String> list = new ArrayList<>();String absolutePath = "";try {String packPath = pack.replace(".", "\\");File src = new File(".\\src");File file = new File(src.getCanonicalPath());File[] fs = file.listFiles();for (int i = 0; i < fs.length; i++) {if (fs[i].isDirectory()) {if (fs[i].getAbsolutePath().endsWith(packPath)) {absolutePath = fs[i].getAbsolutePath() + "\\" + name + suffix;return absolutePath;}list.add(fs[i].getAbsolutePath());}}for (int j = 0; j < Integer.MAX_VALUE; j++) {if (j>0&&j == list.size() - 1) {break;}File tmp = new File(list.get(j));fs = tmp.listFiles();for (int k = 0; k < fs.length; k++) {if (fs[k].isDirectory()) {if (fs[k].getAbsolutePath().endsWith(packPath)) {absolutePath = fs[k].getAbsolutePath() + "\\" + name + suffix;return absolutePath;}list.add(fs[k].getAbsolutePath());}}}} catch (Exception e) {e.printStackTrace();}return absolutePath;}public static String loadFile(String path) {File file = new File(path);String str = null;BufferedReader reader = null;StringBuffer buffer = new StringBuffer();String charset = "utf-8";try {InputStreamReader is = new InputStreamReader(new FileInputStream(file), charset);reader = new BufferedReader(is);while ((str = reader.readLine()) != null) {buffer.append(str);buffer.append("\n");}} catch (IOException e) {e.printStackTrace();} finally {if (reader != null) {try {reader.close();} catch (Exception e) {e.printStackTrace();}}}return buffer.toString();}public static void writeFile(String filePath, String str, boolean flg) {try {FileWriter fw = new FileWriter(new File(filePath), flg);PrintWriter pw = new PrintWriter(fw);pw.println(str);log.info("写入成功。。。");pw.close();} catch (IOException e) {e.printStackTrace();}}public static void writeFile(String filePath, String str) {try {FileWriter fw = new FileWriter(new File(filePath), true);PrintWriter pw = new PrintWriter(fw);pw.println(str);log.info("写入成功。。。");pw.close();} catch (IOException e) {e.printStackTrace();}}//首字母大写public static String upInitials(String str){StringBuffer buff = new StringBuffer();buff.append(String.valueOf(str.charAt(0)).toUpperCase());buff.append(str.toCharArray(),1,str.length()-1);return buff.toString();}
}

构建类

package auto_get_set;import java.lang.reflect.Field;import common.Common;
import common.Templates;
/*** @author vvxtoys*/
public class ClassGenerator {private String [] attrs;private String [] types;private String absolutePath;private String context;private String clazz;public ClassGenerator(Object obj) {loadClass(obj);}public void loadClass(Object obj){Field [] fs = null;try{String claname = obj.getClass().getSimpleName();String suffix = ".java";String pack   = obj.getClass().getPackage().getName();absolutePath = Common.absolutePath(pack, claname, suffix);context = Common.loadFile(absolutePath);clazz = claname;Class clazz = Class.forName(obj.getClass().getName());fs = clazz.getDeclaredFields();attrs = new String[fs.length];types = new String[fs.length];for(int i=0;i<fs.length;i++){attrs[i] = fs[i].getName();types[i] = fs[i].getType().getSimpleName();}}catch(Exception e){e.printStackTrace();}}public void autoGetSet(){String str = context.substring(0,context.lastIndexOf("}"));String get_set = "";for(int i=0;i<attrs.length;i++){String g1 = Templates.format(Templates.T_GET, types[i],Common.upInitials(attrs[i]),attrs[i]);String s1 = Templates.format(Templates.T_SET, Common.upInitials(attrs[i]),types[i],attrs[i]);get_set+=g1+s1;}str+=get_set;str+="}";context = str;}public void autoConstruct(){String str = context.substring(0,context.lastIndexOf("}"));String c1 = Templates.format(Templates.T_CONSTRUCT, clazz,"","");String params = "";String field = "";for(int i=0;i<attrs.length;i++){params+=types[i]+" "+attrs[i]+",";field+=Templates.format(Templates.T_ATTR2, attrs[i]);}params = params.substring(0,params.length()-1);String c2 = Templates.format(Templates.T_CONSTRUCT, clazz,params,field);str +=c1+c2;str+="}";context = str;}public void updateClass(){Common.writeFile(absolutePath, context,false);}public void run(){autoConstruct();autoGetSet();updateClass();}}

测试

package auto_get_set;import cc.vvxtoys.pojo.Student;public class Test {public static void main(String[] args) {ClassGenerator g = new ClassGenerator(new Student());g.run();    }}

构建之后的实体类

package cc.vvxtoys.pojo;public class Student {private int id;private String name;private String sex;private String school;public Student() {super();}public Student(int id,String name,String sex,String school) {super();this.id=id;this.name=name;this.sex=sex;this.school=school;}public int getId () {return id;}public void setId(int id) {this.id=id;}public String getName () {return name;}public void setName(String name) {this.name=name;}public String getSex () {return sex;}public void setSex(String sex) {this.sex=sex;}public String getSchool () {return school;}public void setSchool(String school) {this.school=school;}
}

结束

写写停停大概也是花费了两天的时间，东西虽然很小，也还有bug，但是还是有点成就感的。我知道IDE肯定不可能用这么蠢得实现方式，但是以我现在的想法只能这样了，还是需要多学点东西，然后我再重构这些代码。