基于json-lib.jar包的java转换为 json对象

java与json对象互转

基于json-lib.jar包Json程序,本篇主要介绍一个简单的实例！

1.首先Json-lib 需要至少有下列几个jar包的支持

jakarta commons-lang 2.4

jakarta commons-beanutils 1.7.0

jakarta commons-collections 3.2

jakarta commons-logging 1.1.1

ezmorph 1.0.6

2.Java集合类型arrays,collections同JSONArray的转换

示例1：
boolean[] boolArray = new boolean[] { true, false, true };
JSONArray jsonArray = JSONArray.fromObject(boolArray);
System.out.println(jsonArray);
输出：[true,false,true]

示例2：
List list = new ArrayList();
list.add( "first" );
list.add( "second" );
JSONArray jsonArray = JSONArray.fromObject( list );
System.out.println( jsonArray );
输出：["first","second"]

示例3：
JSONArray jsonArray = JSONArray.fromObject( "['json','is','easy']" );
System.out.println( jsonArray );
输出：["json","is","easy"]

3.Java对象类型JavaBean,Maps同JSONObject的转换

示例1：
Map map = new HashMap();
map.put( "name", "json" );
map.put( "bool", Boolean.TRUE );
map.put( "int", new Integer(1) );
map.put( "arr", new String[]{"a","b"} );
map.put( "func", "function(i){ return this.arr[i]; }" );

JSONObject jsonObject = JSONObject.fromObject( map );
System.out.println( jsonObject );
输出：{"func":function(i){ return this.arr[i]; },"arr":["a","b"],"int":1,
"bool":true,"name":"json"}

示例2：
class MyBean{
private String name = "json";
private int pojoId = 1;
private char[] options = new char[]{'a','f'};
private String func1 = "function(i){ return this.options[i]; }";
private JSONFunction func2 = new JSONFunction(new String[]{"i"},
"return this.options[i];");

// getters & setters
...
}
JSONObject jsonObject = JSONObject.fromObject( new MyBean() );
System.out.println( jsonObject );
输出：{"func1":function(i){ return this.options[i]; },"func2":function(i){
return this.options[i]; },"name":"json","options":["a","f"],"pojoId":1}

4. JSON数据对象格式转换为JAVA类型的Beans

示例1(转换为动态的bean)：
String json = "{name=\"json\",bool:true,int:1,double:2.2,
func:function(a){ return a; },array:[1,2]}";
JSONObject jsonObject = JSONObject.fromObject(json);
Object bean = JSONObject.toBean(jsonObject);
assertEquals(jsonObject.get("name"), PropertyUtils.getProperty(bean, "name"));
assertEquals(jsonObject.get("bool"), PropertyUtils.getProperty(bean, "bool"));
assertEquals(jsonObject.get("int"), PropertyUtils.getProperty(bean, "int"));
assertEquals(jsonObject.get("double"),PropertyUtils.getProperty(bean,"double"));
assertEquals(jsonObject.get("func"), PropertyUtils.getProperty(bean, "func"));
输出：junit测试显示为绿条，即值相等。
示例2(转换为具体的bean)：
String json = "{bool:true,integer:1,string:\"json\"}";
JSONObject jsonObject = JSONObject.fromObject(json);
BeanA bean = (BeanA) JSONObject.toBean(jsonObject, BeanA.class);
assertEquals(jsonObject.get("bool"), Boolean.valueOf(bean.isBool()));
assertEquals(jsonObject.get("integer"), new Integer(bean.getInteger()));
assertEquals(jsonObject.get("string"), bean.getString());
注：BeanA是具体相关属性的getters & setters方法的具体javaBean

5.Java-Json相互转换过滤器--把java类型转换为json时属性的过滤，下面我们再以3中的实例1来做个演示：

实例1：
Map map = new HashMap();
map.put("name", "json");
map.put("bool", Boolean.TRUE);
map.put("int", new Integer(1));
map.put("arr", new String[] { "a", "b" });
map.put("func", "function(i){ return this.arr[i]; }");
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.setJsonPropertyFilter(new PropertyFilter() {
public boolean apply(Object source, String name, Object value) {
if (value != null && Number.class.isAssignableFrom(value.getClass())) {
return true;
}
return false;
}
});
JSONObject json = JSONObject.fromObject(map, jsonConfig);
System.out.println(json);
输出：{"func":function(i){ return this.arr[i]; },"arr":["a","b"],
"bool":true,"name":"json"}
和上面的输出：{"func":function(i){ return this.arr[i]; },"arr":["a","b"],"int":1,"bool":true,"name":"json"}
它少了："int":1,这段，这就是属性过滤器发挥了作用，看代码就可以知道它把值为Number型的都给过滤掉了。
实例2：
如果我们把上例中的Number.class.isAssignableFrom(value.getClass())中的Number改为String呢？
Map map = new HashMap();
map.put("name", "json");
map.put("bool", Boolean.TRUE);
map.put("int", new Integer(1));
map.put("arr", new String[] { "a", "b" });
map.put("func", "function(i){ return this.arr[i]; }");
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.setJsonPropertyFilter(new PropertyFilter() {
public boolean apply(Object source, String name, Object value) {
if (value != null && String.class.isAssignableFrom(value.getClass())) {
//这里是过滤的关键
return true;
}
return false;
}
});
JSONObject json = JSONObject.fromObject(map, jsonConfig);
System.out.println(json);
输出：{"arr":["a","b"],"int":1,"bool":true}
//它把Value的类型为String的都给过滤掉了。

6.Json-Java相互转换过滤器--同5相反这次--把json-转换为java时属性的过滤，下面我们以4中的实例1来做个演示：

实例1：
String json = "{name=\"json\",bool:true,int:1,double:2.2,
func:function(a){ return a; },array:[1,2]}";
JSONObject jsonObject = JSONObject.fromObject(json);
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.setRootClass(Map.class);
jsonConfig.setJavaPropertyFilter(new PropertyFilter() {
public boolean apply(Object source, String name, Object value) {
if ("bool".equals(name) || "double".equals(name)) {//这里是过滤的关键
return true;
}
return false;
}
});
Object bean = JSONObject.toBean(jsonObject, jsonConfig);
System.out.println(bean);
输出：{func=function(a){ return a; }, int=1, name=json, array=[1, 2]}
同4中的实例1输出：{double=2.2, func=function(a){ return a; }, int=1, name=json, bool=true, array=[1, 2]}
少了：double=2.2, bool=true,因为name为bool和double的项已经被过滤掉了。
实例2：
String json = "{name=\"json\",bool:true,int:1,double:2.2,func:function(a){
return a; },array:[1,2]}";
JSONObject jsonObject = JSONObject.fromObject(json);
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.setRootClass(Map.class);
jsonConfig.setJavaPropertyFilter(new PropertyFilter() {
public boolean apply(Object source, String name, Object value) {
if (value != null && String.class.isAssignableFrom(value.getClass())) {
// 这里是过滤的关键
return true;
}
return false;
}
});
Object bean = JSONObject.toBean(jsonObject, jsonConfig);
System.out.println(bean);
输出：{double=2.2, func=function(a){ return a; }, int=1, bool=true, array=[1, 2]}
由此可见，无论是java转换为json还是json转换为java，过滤器都可以根据name和value来过滤。