java动态生成java文件_【Java】动态生成Java代码并编译class文件加载

Created by KdMobiB on 2017/7/11.

*/

public class Utils {

File file;//java文件的生成目录

String rootName;

/**

开始解析Json数据

@param jsonStr

@return

*/

@SuppressWarnings("unchecked")

public HashMap getRootFromJson(String rootClass, String jsonStr) {

LinkedTreeMap a = new Gson().fromJson(jsonStr, LinkedTreeMap.class);

return getKidFromJson(rootClass, a, true);

}

public HashMap getListRootFromJson(String rootClass, String jsonStr) {

LinkedTreeMap a = new Gson().fromJson(jsonStr, LinkedTreeMap.class);

startChildArrayClass(rootClass);

return getKidFromJson(rootClass, a, false);

}

/**

WRITE THE KIDCLASS

@param a

@return

*/

public HashMap getKidFromJson(String childClass, LinkedTreeMap a, boolean disable) {

if ((!rootName.equals(childClass)) && disable) {

startChildClass(childClass);

}

HashMap maps = new HashMap();

Set> entry = a.entrySet();

Iterator> iterator = entry.iterator();

while (iterator.hasNext()) {

LinkedTreeMap.Entry stringObjectEntry = iterator.next();

String sk = stringObjectEntry.getKey();

Object sv = stringObjectEntry.getValue();

if (sv instanceof LinkedTreeMap) {

//如果TreeMap类型，代表数据还有分支，继续遍历下去

getKidFromJson(sk, (LinkedTreeMap) sv, true);

stopChildClass();

} else if (sv instanceof ArrayList) {

//如果是List类型，列表内的数据需要重新创建一个类

getListRootFromJson(sk, new Gson().toJson(((ArrayList) sv).get(0)));

stopChildClass();

} else {

//当判断不是数组类型或者列表类型，直接将key写入当前的类

sb.append("t" + sv.getClass().getSimpleName() + " " + sk + ";tn");

addGetAndSet(sb, sk, sv.getClass().getSimpleName());

}

maps.put(sk, sv);

}

return maps;

}

StringBuilder sb = new StringBuilder("rn");

/**

开始

@param root

*/

public void startFileWrite(String root) {

rootName = root;

file = new File(getClass().getResource("").getFile() + "/" + root + ".java");

sb.append(getClass().getPackage() + ";" + "rn");

sb.append("public class " + root + "{" + "rn");

}

/**

结束

*/

public void finishFileWrite() {

try {

FileWriter fw = new FileWriter(file);

sb.append("rn");

sb.append("}");

fw.write(sb.toString());

fw.flush();

fw.close();

} catch (IOException e) {

e.printStackTrace();

}

}

public void startChildClass(String childName) {

String childClass = childName + "Class";

sb.append("public " + childClass + " " + childName + ";rn");

sb.append("class " + childClass);

sb.append("{" + "rn");

}

public void startChildArrayClass(String childName) {

addLibsImport("import java.util.ArrayList;");

String childClass = childName + "Class";

sb.append("public ArrayList " + childName + ";rn");

sb.append("class " + childClass);

sb.append("{" + "rn");

}

public void stopChildClass() {

sb.append("rn");

sb.append("}");

}

/**

编写Java文件

@param maps

*/

public void writeInJava(HashMap maps) {

Iterator> iterator = maps.entrySet().iterator();

while (iterator.hasNext()) {

LinkedTreeMap.Entry entry = iterator.next();

if (entry.getValue() instanceof LinkedTreeMap) return;

String key = entry.getKey();

String FieldType = entry.getValue().getClass().getSimpleName();

sb.append("rnt");

sb.append("public " + FieldType + " " + key + ";");

sb.append("rnt");

addGetAndSet(sb, key, FieldType);

}

}

public void addGetAndSet(StringBuilder sb, String name, String type) {

sb.append("rnt");

sb.append("public void " + "set" + name);

sb.append("(" + type + " " + name + "1" + ")");

sb.append("{");

sb.append("rntt");

sb.append("this." + name + "=" + name + "1" + ";");

sb.append("rnt");

sb.append("}");

sb.append("rnt");

sb.append("public " + type + " " + "get" + name);

sb.append("(" + ")");

sb.append("{");

sb.append("rntt");

sb.append("return " + name + ";");

sb.append("rnt");

sb.append("}");

sb.append("rn");

}

/**

编译生成的Java文件

*/

public void complie2Class() {

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

StandardJavaFileManager fileMgr = compiler.getStandardFileManager(null, null, null);

Iterable units = fileMgr.getJavaFileObjects(file);

JavaCompiler.CompilationTask t = compiler.getTask(null, fileMgr, null, null, null, units);

t.call();

try {

fileMgr.close();

} catch (IOException e) {

e.printStackTrace();

}

}

/**

通过Url加载生成Class文件

@param className

*/

public void loadClass(String className) {

String fileUrl = "file:/" + file.getParent();

System.out.println(fileUrl);

try {

URL[] urls = new URL[]{new URL(fileUrl)};

URLClassLoader ul = new URLClassLoader(urls, ClassLoader.getSystemClassLoader());

Class c = ul.loadClass(getClass().getPackage().getName() + "." + className);

System.out.println(c.newInstance().getClass().getName());

Object o = c.newInstance();

} catch (MalformedURLException e) {

e.printStackTrace();

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (InstantiationException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

}

}

/**

添加第三方导包

*/

public void addLibsImport(String lib) {

String regex = getClass().getPackage() + ";" + "rn";

if (!sb.toString().contains(lib)) {

sb.insert(sb.indexOf(regex) + regex.length(), "rn" + lib + "rn");

}

}

}