一直以来，有个目标是：使用Beetl的时候，如果web root 里有模板文件，则beetl从web root里加载。如果没有，则从jar里加载，或者从Db里加载。

这样，工程里大量相同的模板模板可以共用(当你的应用，有N个客户的时候，特别需要这个，更新一个jar，重启一下即可)。

最后确认CompositeResourceLoader 无法满足自己的需求。于是磕磕碰碰的自己实现了一个ResourceLoader，自定义加载模板。

直接贴代码吧

package com.jfinal.ext.beetl;

import java.io.File;

import java.net.URL;

import java.util.Map;

import org.beetl.core.GroupTemplate;

import org.beetl.core.Resource;

import org.beetl.core.ResourceLoader;

import org.beetl.core.misc.BeetlUtil;

/**

* 自定义的ResourceLoader，用于支持从文件，jar和数据库里加载模板。

* @author Neoman

*/

public class AppResourceLoader implements ResourceLoader{

private String root = null;

boolean autoCheck = false;

//模板来自文件

boolean fromFile = true;

//模板来自Db

boolean fromDb = false;

//模板来自jar包

boolean fromJar = false;

protected String charset = "UTF-8";

String functionRoot = "functions";

GroupTemplate gt = null;

String functionSuffix = "fn";

ClassLoader classLoader = null;

/**

* 使用加载beetl.jar的classloader，以及默认root为根目录

*/

public AppResourceLoader()

{

//保留，用于通过配置构造一个ResouceLoader

classLoader = this.getClass().getClassLoader();

this.root = "";

}

/** 使用指定的classloader

* @param classLoader

*/

public AppResourceLoader(ClassLoader classLoader)

{

this.classLoader = classLoader;

this.root = "";

}

/**使用指定的classloader和root

* @param classLoader

* @param root 模板路径，如/com/templates/

*/

public AppResourceLoader(ClassLoader classLoader, String root)

{

this.classLoader = classLoader;

this.root = root;

}

/**

* @param classLoader

* @param root

* @param charset

*/

public AppResourceLoader(ClassLoader classLoader, String root, String charset)

{

this(classLoader, root);

this.charset = charset;

}

/**

* @param root ，/com/templates/如其后的resourceId对应的路径是root+"/"+resourceId

*/

public AppResourceLoader(String root)

{

this();

if (root.equals("/"))

{

this.root = "";

}

else

{

this.root = root;

}

}

public AppResourceLoader(String root, String charset)

{

this(root);

this.charset = charset;

}

/*

* (non-Javadoc)

*

* @see org.beetl.core.ResourceLoader#getResource(java.lang.String)

*/

@Override

public Resource getResource(String key)

{

AppResource resource = new AppResource(root, key, this);

resource.setFromFile(fromFile);

resource.setFromDb(fromDb);

resource.setFromJar(fromJar);

return resource;

}

/*

* (non-Javadoc)

*

* @see org.beetl.core.ResourceLoader#close()

*/

@Override

public void close()

{

// TODO Auto-generated method stub

}

@Override

public boolean isModified(Resource key)

{

if (this.autoCheck)

{

return key.isModified();

}

else

{

return false;

}

}

public boolean isAutoCheck()

{

return autoCheck;

}

public void setAutoCheck(boolean autoCheck)

{

this.autoCheck = autoCheck;

}

public String getRoot()

{

return root;

}

@Override

public void init(GroupTemplate gt)

{

Map resourceMap = gt.getConf().getResourceMap();

if (resourceMap.get("root") != null)

{

String temp = resourceMap.get("root");

if (temp.equals("/") || temp.length() == 0)

{

}

else

{

if (this.root.endsWith("/"))

{

this.root = this.root + resourceMap.get("root");

}

else

{

this.root = this.root + "/" + resourceMap.get("root");

}

}

}

if (this.charset == null)

{

this.charset = resourceMap.get("charset");

}

this.functionSuffix = resourceMap.get("functionSuffix");

this.autoCheck = Boolean.parseBoolean(resourceMap.get("autoCheck"));

this.functionRoot = resourceMap.get("functionRoot");

//初始化functions

URL url = classLoader.getResource("");

this.gt = gt;

if (url!=null&&url.getProtocol().equals("file"))

{

File fnRoot = new File(url.getFile() + File.separator + root + File.separator + this.functionRoot);

if (fnRoot.exists())

{

String ns = "";

String path = "/".concat(this.functionRoot).concat("/");

BeetlUtil.autoFileFunctionRegister(gt, fnRoot, ns, path, this.functionSuffix);

}

}

}

@Override

public boolean exist(String key)

{

URL url = this.classLoader.getResource(root + key);

if(url==null){

//兼容以前的

url = this.classLoader.getClass().getResource(root + key);

}

return url!=null;

}

public String getCharset()

{

return charset;

}

public void setCharset(String charset)

{

this.charset = charset;

}

@Override

public String getResourceId(Resource resource, String id)

{

if (resource == null)

return id;

else

return BeetlUtil.getRelPath(resource.getId(), id);

}

public ClassLoader getClassLoader() {

return classLoader;

}

public void setClassLoader(ClassLoader classLoader) {

this.classLoader = classLoader;

}

@Override

public String getInfo() {

return "ClassLoader:"+this.classLoader+" Path:"+root;

}

public boolean isFromFile() {

return fromFile;

}

public void setFromFile(boolean fromFile) {

this.fromFile = fromFile;

}

public boolean isFromDb() {

return fromDb;

}

public void setFromDb(boolean fromDb) {

this.fromDb = fromDb;

}

public boolean isFromJar() {

return fromJar;

}

public void setFromJar(boolean fromJar) {

this.fromJar = fromJar;

}

}

AppResourceLoader基本复制之前org.beetl.core.resource.WebAppResourceLoader的。init 注册函数的时候，还是仅仅读取web root里的目录。因为我自己的是代码里注册了，所以，也没去实现从jar加载function

package com.jfinal.ext.beetl;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.Reader;

import java.io.UnsupportedEncodingException;

import java.net.URL;

import org.beetl.core.Resource;

import org.beetl.core.ResourceLoader;

import org.beetl.core.exception.BeetlException;

import com.jfinal.kit.PathKit;

/**

* 模板资源读取，支持从db，文件，classpath，jar 里读取模板资源：

* 先从webroot的文件里读取，如果没有，则读取数据库，如何还找不到，读取jar或者classpath里的

* @author Neoman

*

*/

public class AppResource extends Resource{

String root = null;

File file = null;

long lastModified = 0;

//模板来自文件

boolean fromFile = true;

//模板来自Db

boolean fromDb = false;

//模板来自jar包

boolean fromJar = false;

public AppResource(String root, String key, ResourceLoader resourceLoader)

{

super(key, resourceLoader);

this.root = root;

}

@Override

public Reader openReader()

{

InputStream is = null;

Reader br;

AppResourceLoader loader = (AppResourceLoader) this.resourceLoader;

try

{//从文件里读取，一般的web root里

file = new File(PathKit.getWebRootPath() + root, id);

if (file.exists() && fromFile) {

is = new FileInputStream(file);

}

//从数据库里读取,暂未实现

if (is == null && fromDb) {

}

//从jar 或者classpath里读取

if (is == null && fromJar) {

ClassLoader cs = loader.getClassLoader();

URL url = cs.getResource(root + id);

if(url==null){

//兼容以前的写法

url = resourceLoader.getClass().getResource(root + id);

}

if (url == null)

{

BeetlException be = new BeetlException(BeetlException.TEMPLATE_LOAD_ERROR);

be.resourceId = this.id;

throw be;

}

is = url.openStream();

}

if (is == null) {

BeetlException be = new BeetlException(BeetlException.TEMPLATE_LOAD_ERROR, " 模板不存在: " + loader.getInfo());

be.resourceId = this.id;

throw be;

}

br = new BufferedReader(new InputStreamReader(is, loader.charset));

return br;

}

catch (UnsupportedEncodingException e)

{

return null;

} catch (FileNotFoundException e) {

// TODO Auto-generated catch block

BeetlException be = new BeetlException(BeetlException.TEMPLATE_LOAD_ERROR, " 模板根目录为 " + loader.getRoot());

be.resourceId = this.id;

throw be;

} catch (IOException e) {

// TODO Auto-generated catch block

BeetlException be = new BeetlException(BeetlException.TEMPLATE_LOAD_ERROR, " 模板根目录为 " + loader.getRoot());

be.resourceId = this.id;

throw be;

}

}

/**

* 目前，只能跟踪文件的变化

*/

@Override

public boolean isModified()

{

if (fromFile && file != null && file.exists())

{

return file.lastModified() != this.lastModified;

}

//String refresh = SysConfig.dao.queryConfig("beetl.template.refresh", "0");

//if (!"0".equals(refresh)) {//不等于0，刷新模板

//SysConfig.dao.updateConfig("beetl.template.refresh", "0");

//return true;

//}

//jar里，肯定要重启了

if (fromJar)

{

return false;

}

//db里 判断时间--暂未 实现

if (fromDb)

{

return false;

}

return false;

}

@Override

public String getId()

{

return id;

}

public boolean isFromFile() {

return fromFile;

}

public void setFromFile(boolean fromFile) {

this.fromFile = fromFile;

}

public boolean isFromDb() {

return fromDb;

}

public void setFromDb(boolean fromDb) {

this.fromDb = fromDb;

}

public boolean isFromJar() {

return fromJar;

}

public void setFromJar(boolean fromJar) {

this.fromJar = fromJar;

}

}

暂时未用到从db加载，所以没去实现了。不过也很简单了。AppResource 主要是 openReader 里面判断资源从哪里加载。

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