将pojo对象的属性值提取出来，组成json格式的数据代码,Java代码库,德仔网

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【Java】将pojo对象的属性值提取出来，组成json格式的数据
作者: / 发布于2011/1/14/ 801
<div><span style="color: #0000ff">import</span><span style="color: #000000"> java.lang.reflect.Field;
</span><span style="color: #0000ff">import</span><span style="color: #000000"> java.util.Collection;
</span><span style="color: #0000ff">import</span><span style="color: #000000"> java.util.Iterator;
</span><span style="color: #008000">/*</span><span style="color: #008000">
* 将pojo对象的属性值提取出来，组成json格式的数据
* 当前版本只能对最基本的pojo对象进行转化，类似于下面的格式：
 public class Pojo {
 private String name;
 private int age;
 public int getAge() { 
 return age; 
 } 
 
 public String getName() { 
 return name; 
 } 
 
 public void setAge(int age) { 
 this.age = age; 
 } 
 
 public void setName(String name) { 
 this.name = name; 
 } 
 
 }
* 单个对象返回{'name':age}格式；集合对象返回{'name':age},{'name':age}...
* 
* author：scriptguy
* date： 2010/04/06
</span><span style="color: #008000">*/</span><span style="color: #000000">
</span><span style="color: #0000ff">public</span><span style="color: #000000"> </span><span style="color: #0000ff">class</span><span style="color: #000000"> JsonUtil {
 
 </span><span style="color: #008000">/*</span><span style="color: #008000">
 ** 暴露出来的方法，传入需要将属性值转换为json数据格式的pojo
 ** 会抛出IllegalAccessException异常，需要捕捉
 </span><span style="color: #008000">*/</span><span style="color: #000000">
 </span><span style="color: #0000ff">public</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> String toJson(Object obj) </span><span style="color: #0000ff">throws</span><span style="color: #000000"> IllegalAccessException{
 Class cla </span><span style="color: #000000">=</span><span style="color: #000000"> obj.getClass();
 Field[] fields </span><span style="color: #000000">=</span><span style="color: #000000"> cla.getDeclaredFields();
 String[] names </span><span style="color: #000000">=</span><span style="color: #000000"> fieldToNames(fields);
 Object[] values </span><span style="color: #000000">=</span><span style="color: #000000"> fieldToValues(fields,obj);
 String json </span><span style="color: #000000">=</span><span style="color: #000000"> produceToJson(names,values);
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> json;
 }
 
 </span><span style="color: #0000ff">private</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> String[] fieldToNames(Field[] fields) {
 String[] names </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> String[fields.length];
 </span><span style="color: #0000ff">for</span><span style="color: #000000">(</span><span style="color: #0000ff">int</span><span style="color: #000000"> i </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">;i </span><span style="color: #000000"><</span><span style="color: #000000"> fields.length;i</span><span style="color: #000000">++</span><span style="color: #000000">) {
 fields[i].setAccessible(</span><span style="color: #0000ff">true</span><span style="color: #000000">);</span><span style="color: #008000">//</span><span style="color: #008000">将此对象的 accessible 标志设置为可以读取</span><span style="color: #008000">
</span><span style="color: #000000"> names[i] </span><span style="color: #000000">=</span><span style="color: #000000"> fields[i].getName();
 }
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> names;
 }
 
 </span><span style="color: #0000ff">private</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> Object[] fieldToValues(Field[] fields,Object obj) </span><span style="color: #0000ff">throws</span><span style="color: #000000"> IllegalAccessException{
 Object[] values </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> Object[fields.length];
 </span><span style="color: #0000ff">for</span><span style="color: #000000">(</span><span style="color: #0000ff">int</span><span style="color: #000000"> i </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">;i </span><span style="color: #000000"><</span><span style="color: #000000"> fields.length;i</span><span style="color: #000000">++</span><span style="color: #000000">) {
 values[i] </span><span style="color: #000000">=</span><span style="color: #000000"> fields[i].get(obj);
 }
 
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> values;
 }
 
 </span><span style="color: #0000ff">private</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> String produceToJson(String[] names,Object[] values) {
 </span><span style="color: #0000ff">if</span><span style="color: #000000">(names.length </span><span style="color: #000000">!=</span><span style="color: #000000"> values.length) {
 </span><span style="color: #0000ff">new</span><span style="color: #000000"> RuntimeException(</span><span style="color: #000000">"</span><span style="color: #000000">转化json数据出错！！！</span><span style="color: #000000">"</span><span style="color: #000000">); 
 }
 StringBuilder json </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> StringBuilder();
 json.append(</span><span style="color: #000000">"</span><span style="color: #000000">{</span><span style="color: #000000">"</span><span style="color: #000000">);
 </span><span style="color: #0000ff">for</span><span style="color: #000000">(</span><span style="color: #0000ff">int</span><span style="color: #000000"> i </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">;i </span><span style="color: #000000"><</span><span style="color: #000000"> names.length;i</span><span style="color: #000000">++</span><span style="color: #000000">) {
 json.append(</span><span style="color: #000000">"</span><span style="color: #000000">'</span><span style="color: #000000">"</span><span style="color: #000000">);
 json.append(names[i]);
 json.append(</span><span style="color: #000000">"</span><span style="color: #000000">':</span><span style="color: #000000">"</span><span style="color: #000000">);
 processFieldValue(values[i],json);
 </span><span style="color: #0000ff">if</span><span style="color: #000000">(i </span><span style="color: #000000"><</span><span style="color: #000000"> names.length </span><span style="color: #000000">-</span><span style="color: #000000"> </span><span style="color: #000000">1</span><span style="color: #000000">) {
 json.append(</span><span style="color: #000000">"</span><span style="color: #000000">,</span><span style="color: #000000">"</span><span style="color: #000000">);
 }
 }
 json.append(</span><span style="color: #000000">"</span><span style="color: #000000">}</span><span style="color: #000000">"</span><span style="color: #000000">);
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> json.toString();
 }
 
 </span><span style="color: #0000ff">private</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> </span><span style="color: #0000ff">void</span><span style="color: #000000"> processFieldValue(Object obj,StringBuilder json) {
 </span><span style="color: #0000ff">if</span><span style="color: #000000">(obj </span><span style="color: #0000ff">instanceof</span><span style="color: #000000"> Number) {
 json.append(obj);
 } </span><span style="color: #0000ff">else</span><span style="color: #000000"> {
 json.append(</span><span style="color: #000000">"</span><span style="color: #000000">'</span><span style="color: #000000">"</span><span style="color: #000000">);
 json.append(obj);
 json.append(</span><span style="color: #000000">"</span><span style="color: #000000">'</span><span style="color: #000000">"</span><span style="color: #000000">);
 }
 }
 
 </span><span style="color: #0000ff">public</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> String allToJson(Collection coll) </span><span style="color: #0000ff">throws</span><span style="color: #000000"> IllegalAccessException{
 Iterator iterator </span><span style="color: #000000">=</span><span style="color: #000000"> coll.iterator();
 StringBuilder json </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> StringBuilder();
 Object obj;
 </span><span style="color: #0000ff">while</span><span style="color: #000000">(iterator.hasNext()) {
 obj </span><span style="color: #000000">=</span><span style="color: #000000"> iterator.next();
 json.append(toJson(obj));
 json.append(</span><span style="color: #000000">"</span><span style="color: #000000">,</span><span style="color: #000000">"</span><span style="color: #000000">);
 }
 </span><span style="color: #0000ff">int</span><span style="color: #000000"> delete </span><span style="color: #000000">=</span><span style="color: #000000"> json.lastIndexOf(</span><span style="color: #000000">"</span><span style="color: #000000">,</span><span style="color: #000000">"</span><span style="color: #000000">);
 json </span><span style="color: #000000">=</span><span style="color: #000000"> json.deleteCharAt(delete);
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> json.toString();
 }
 
 
 </span><span style="color: #008000">/*</span><span style="color: #008000">
 **
 </span><span style="color: #008000">*/</span><span style="color: #000000">
}
</span><span style="color: #0000ff">import</span><span style="color: #000000"> java.util.Collection;
</span><span style="color: #0000ff">import</span><span style="color: #000000"> java.util.</span><span style="color: #000000">*</span><span style="color: #000000">;
</span><span style="color: #0000ff">public</span><span style="color: #000000"> </span><span style="color: #0000ff">class</span><span style="color: #000000"> TestJsonUtil {
 </span><span style="color: #0000ff">public</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> </span><span style="color: #0000ff">void</span><span style="color: #000000"> main(String[] args) </span><span style="color: #0000ff">throws</span><span style="color: #000000"> Exception{
 Pojo pojo1 </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> Pojo(</span><span style="color: #000000">"</span><span style="color: #000000">list</span><span style="color: #000000">"</span><span style="color: #000000">,</span><span style="color: #000000">23</span><span style="color: #000000">);
 Pojo pojo </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> Pojo(</span><span style="color: #000000">"</span><span style="color: #000000">scriptguy</span><span style="color: #000000">"</span><span style="color: #000000">,</span><span style="color: #000000">22</span><span style="color: #000000">);
 List</span><span style="color: #000000"><</span><span style="color: #000000">Object</span><span style="color: #000000">></span><span style="color: #000000"> lista </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> ArrayList</span><span style="color: #000000"><</span><span style="color: #000000">Object</span><span style="color: #000000">></span><span style="color: #000000">();
 lista.add(pojo1);
 lista.add(pojo);
 System.out.println(JsonUtil.allToJson(lista));
 }

}

</span>


结果：
 {'name':'list','age':23},{'name':'scriptguy','age':22}

</div>
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