java中List对象转换为JSON对象
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Java知识 2011-11-22 14:12
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java中List对象转换为JSON对象
以为兄弟写的！感觉风格颇为幽默，自恋的来说，很像我的风格哦！呵呵！
好啦！帮他的成果复制过来吧！
一、什么是JSON
JSON 即 JavaScript Object Natation(Java对象表示法)，它是一种轻量级的数据交换格式，非常适合于服务器与 JavaScript 的交互。
简而言之，JSON就是JavaScript交换数据的一种格式。例子如下：
<span style="color:#ff0000;FONT-SIZE: 16px"><strong>{"username":"coolcooldool","password":"1230","usertype":"superadmin"}</strong></span><span style="color:#ff0000;FONT-SIZE: 16px"><strong>{"list":[{"password":"1230","username":"coolcooldool"},{"password":"thisis2","username":"okokok"}]}</strong></span><span style="color:#274e13;FONT-SIZE: 16px">第二种是有数组的情况，我也不用文字表述JSON到底是怎么构成的了，相信长眼睛的人都看懂了，哇咔咔！~</span>
<span style="font-size:24px;color:#ff00ff;"><strong>二、为什么使用JSON而不是XML</strong></span>
他们都是这样说的：
<span style="color:#0000ff;FONT-SIZE: 13px"><em>尽管有许多宣传关于 XML 如何拥有跨平台，跨语言的优势，然而，除非应用于 Web Services，否则，在普通的 Web 应用中，开发者经常为 XML 的解析伤透了脑筋，无论是服务器端生成或处理 XML，还是客户端用 JavaScript 解析 XML，都常常导致复杂的代码，极低的开发效率。实际上，对于大多数 Web 应用来说，他们根本不需要复杂的 XML 来传输数据，XML 的扩展性很少具有优势，许多 AJAX 应用甚至直接返回 HTML 片段来构建动态 Web 页面。和返回 XML 并解析它相比，返回 HTML 片段大大降低了系统的复杂性，但同时缺少了一定的灵活性。</em></span>
<span style="color:#ff0000;"><span style="color:#000000;">我认为就是说：</span><strong>解析XML太费劲了。</strong></span>
<span style="font-size:24px;color:#ff00ff;"><strong>三、如何使用</strong></span>
<span style="color:#274e13;FONT-SIZE: 16px"><span style="color:#000000;"> </span>当然最直接的方法就是，你自己写一个类，把你在数据库中查到的list转换成Sting,格式就是JSON样子的就行，但前提是你比较牛叉，能很快写出来，并且是对的，对于我这么不牛叉的人来说，我选第二种方法。</span>
<span style="color:#274e13;FONT-SIZE: 16px"> 去网上找别人写好的类，看一遍，拿过来用就好了。我目前找到了两个类，都能达到效果，待我慢慢道来。</span>
1.在你的MyEclipse里新建一个Web Project,就叫<strong><span style="color:#ff0000;">Ajax_Json</span></strong>吧。
2.新建一个类，名字叫做<span style="color:#ff0000;"><strong>JsonUtil.java</strong></span>，打包到<strong><span style="color:#ff0000;">young.ajax.json</span></strong>，把下面代码复制进去。
[java]
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package young.ajax.json; import java.beans.IntrospectionException; import java.beans.Introspector; import java.beans.PropertyDescriptor; import java.math.BigDecimal; import java.math.BigInteger; import java.util.List; import java.util.Map; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; public class JsonUtil { private static Log log = LogFactory.getLog(JsonUtil.class); public static String object2json(Object obj) { StringBuilder json = new StringBuilder(); if (obj == null) { json.append(""""); } else if (obj instanceof String || obj instanceof Integer || obj instanceof Float || obj instanceof Boolean || obj instanceof Short || obj instanceof Double || obj instanceof Long || obj instanceof BigDecimal || obj instanceof BigInteger || obj instanceof Byte) { json.append(""").append(string2json(obj.toString())).append("""); } else if (obj instanceof Object[]) { json.append(array2json((Object[]) obj)); } else if (obj instanceof List) { json.append(list2json((List<?>) obj)); } else if (obj instanceof Map) { json.append(map2json((Map<?, ?>) obj)); } else if (obj instanceof Set) { json.append(set2json((Set<?>) obj)); } else { json.append(bean2json(obj)); } return json.toString(); } public static String bean2json(Object bean) { StringBuilder json = new StringBuilder(); json.append("{"); PropertyDescriptor[] props = null; try { props = Introspector.getBeanInfo(bean.getClass(), Object.class).getPropertyDescriptors(); } catch (IntrospectionException e) {} if (props != null) { for (int i = 0; i < props.length; i++) { try { String name = object2json(props[i].getName()); String value = object2json(props[i].getReadMethod().invoke(bean)); json.append(name); json.append(":"); json.append(value); json.append(","); } catch (Exception e) {} } json.setCharAt(json.length() - 1, '}'); } else { json.append("}"); } return json.toString(); } public static String list2json(List<?> list) { StringBuilder json = new StringBuilder(); json.append("["); if (list != null && list.size() > 0) { for (Object obj : list) { json.append(object2json(obj)); json.append(","); } json.setCharAt(json.length() - 1, ']'); } else { json.append("]"); } return json.toString(); } public static String array2json(Object[] array) { StringBuilder json = new StringBuilder(); json.append("["); if (array != null && array.length > 0) { for (Object obj : array) { json.append(object2json(obj)); json.append(","); } json.setCharAt(json.length() - 1, ']'); } else { json.append("]"); } return json.toString(); } public static String map2json(Map<?, ?> map) { StringBuilder json = new StringBuilder(); json.append("{"); if (map != null && map.size() > 0) { for (Object key : map.keySet()) { json.append(object2json(key)); json.append(":"); json.append(object2json(map.get(key))); json.append(","); } json.setCharAt(json.length() - 1, '}'); } else { json.append("}"); } return json.toString(); } public static String set2json(Set<?> set) { StringBuilder json = new StringBuilder(); json.append("["); if (set != null && set.size() > 0) { for (Object obj : set) { json.append(object2json(obj)); json.append(","); } json.setCharAt(json.length() - 1, ']'); } else { json.append("]"); } return json.toString(); } public static String string2json(String s) { if (s == null) return ""; StringBuilder sb = new StringBuilder(); for (int i = 0; i < s.length(); i++) { char ch = s.charAt(i); switch (ch) { case '"': sb.append("\""); break; case '\': sb.append("\"); break; case 'b': sb.append("\b"); break; case 'f': sb.append("\f"); break; case 'n': sb.append("\n"); break; case 'r': sb.append("\r"); break; case 't': sb.append("\t"); break; case '/': sb.append("\/"); break; default: if (ch >= 'u0000' && ch <= 'u001F') { String ss = Integer.toHexString(ch); sb.append("\u"); for (int k = 0; k < 4 - ss.length(); k++) { sb.append('0'); } sb.append(ss.toUpperCase()); } else { sb.append(ch); } } } return sb.toString(); } }
package young.ajax.json;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class JsonUtil {
private static Log log = LogFactory.getLog(JsonUtil.class);
public static String object2json(Object obj) {
StringBuilder json = new StringBuilder();
if (obj == null) {
json.append("""");
} else if (obj instanceof String || obj instanceof Integer || obj instanceof Float
|| obj instanceof Boolean || obj instanceof Short || obj instanceof Double
|| obj instanceof Long || obj instanceof BigDecimal || obj instanceof BigInteger
|| obj instanceof Byte) {
json.append(""").append(string2json(obj.toString())).append(""");
} else if (obj instanceof Object[]) {
json.append(array2json((Object[]) obj));
} else if (obj instanceof List) {
json.append(list2json((List<?>) obj));
} else if (obj instanceof Map) {
json.append(map2json((Map<?, ?>) obj));
} else if (obj instanceof Set) {
json.append(set2json((Set<?>) obj));
} else {
json.append(bean2json(obj));
}
return json.toString();
}
public static String bean2json(Object bean) {
StringBuilder json = new StringBuilder();
json.append("{");
PropertyDescriptor[] props = null;
try {
props = Introspector.getBeanInfo(bean.getClass(), Object.class).getPropertyDescriptors();
} catch (IntrospectionException e) {}
if (props != null) {
for (int i = 0; i < props.length; i++) {
try {
String name = object2json(props[i].getName());
String value = object2json(props[i].getReadMethod().invoke(bean));
json.append(name);
json.append(":");
json.append(value);
json.append(",");
} catch (Exception e) {}
}
json.setCharAt(json.length() - 1, '}');
} else {
json.append("}");
}
return json.toString();
}
public static String list2json(List<?> list) {
StringBuilder json = new StringBuilder();
json.append("[");
if (list != null && list.size() > 0) {
for (Object obj : list) {
json.append(object2json(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
public static String array2json(Object[] array) {
StringBuilder json = new StringBuilder();
json.append("[");
if (array != null && array.length > 0) {
for (Object obj : array) {
json.append(object2json(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
public static String map2json(Map<?, ?> map) {
StringBuilder json = new StringBuilder();
json.append("{");
if (map != null && map.size() > 0) {
for (Object key : map.keySet()) {
json.append(object2json(key));
json.append(":");
json.append(object2json(map.get(key)));
json.append(",");
}
json.setCharAt(json.length() - 1, '}');
} else {
json.append("}");
}
return json.toString();
}
public static String set2json(Set<?> set) {
StringBuilder json = new StringBuilder();
json.append("[");
if (set != null && set.size() > 0) {
for (Object obj : set) {
json.append(object2json(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
public static String string2json(String s) {
if (s == null)
return "";
StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
char ch = s.charAt(i);
switch (ch) {
case '"':
sb.append("\"");
break;
case '\':
sb.append("\\");
break;
case 'b':
sb.append("\b");
break;
case 'f':
sb.append("\f");
break;
case 'n':
sb.append("\n");
break;
case 'r':
sb.append("\r");
break;
case 't':
sb.append("\t");
break;
case '/':
sb.append("\/");
break;
default:
if (ch >= 'u0000' && ch <= 'u001F') {
String ss = Integer.toHexString(ch);
sb.append("\u");
for (int k = 0; k < 4 - ss.length(); k++) {
sb.append('0');
}
sb.append(ss.toUpperCase());
} else {
sb.append(ch);
}
}
}
return sb.toString();
}
}
这应该是一个高手自己写的代码，就是用刚才第一种方法的人，哈哈！这个类就能将你的几乎所有类型转换成JSON形式的字符串，你可以自己写个类测试一下，我就不写了。
<span style="color:#0000ff;">呐，到现在为止，我们已经有一种方法能将list型的东东转换成为JSON形式的数据了。但是，偷偷的告诉你，还有一种方法，其实效果是一样的，但是传说是官方的，所以用了会显得比较专业，比较牛叉所以我选了第二种，哇咔咔！</span>[java] view plaincopyprint? package young.ajax.json;import
package young.ajax.json;import[java] view plaincopyprint? java.util.HashMap;
java.util.HashMap;[java] view plaincopyprint? import java.util.List;
import java.util.List;[java] view plaincopyprint? import java.util.Map;
import java.util.Map;[java] view plaincopyprint? import net.sf.json.JSONArray;
import net.sf.json.JSONArray;[java] view plaincopyprint? import net.sf.json.JSONException;
import net.sf.json.JSONException;[java] view plaincopyprint? import net.sf.json.JSONObject;
import net.sf.json.JSONObject;[java] view plaincopyprint? public class JsonConvert
public class JsonConvert[java] view plaincopyprint? { public static JSONObject message(String message, boolean success)
{ public static JSONObject message(String message, boolean success)
[java]
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{ Map map = new HashMap();
{ Map map = new HashMap();
[java]
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map.put("success", success);
map.put("success", success);
[java]
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map.put("message", message);
map.put("message", message);
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return JSONObject.fromObject(map);
return JSONObject.fromObject(map);[java] view plaincopyprint? }
}[java] view plaincopyprint? public static JSONObject generate(List list)
public static JSONObject generate(List list)[java] view plaincopyprint? { Map map = new HashMap();
{ Map map = new HashMap();
[java]
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map.put("totalProperty", list.size());
map.put("totalProperty", list.size());
[java]
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map.put("root", list);
map.put("root", list);
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return JSONObject.fromObject(map);
return JSONObject.fromObject(map);[java] view plaincopyprint? }
}[java] view plaincopyprint? public static JSONObject javabean2json(Object object, String message, boolean success)
public static JSONObject javabean2json(Object object, String message, boolean success)[java] view plaincopyprint? { Map map = new HashMap();
{ Map map = new HashMap();
[java]
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map.put("success", success);
map.put("success", success);
[java]
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map.put("message", message);
map.put("message", message);
[java]
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map.put("data", object);
map.put("data", object);
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return JSONObject.fromObject(map);
return JSONObject.fromObject(map);[java] view plaincopyprint? }
}[java] view plaincopyprint? public static JSONObject objectcollect2json(List list, String total) {
public static JSONObject objectcollect2json(List list, String total) {
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Map map = new HashMap();
Map map = new HashMap();[java] view plaincopyprint? map.put("totalProperty", total);
map.put("totalProperty", total);
[java]
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map.put("root", list);
map.put("root", list);
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return JSONObject.fromObject(map);
return JSONObject.fromObject(map);[java] view plaincopyprint? }
}[java] view plaincopyprint? public static JSONArray getJSONArrayFormString(String str) {
public static JSONArray getJSONArrayFormString(String str) {
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if (str == null || str.trim().length() == 0) {
if (str == null || str.trim().length() == 0) {
[java]
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return null;
return null;[java] view plaincopyprint? }
}[java] view plaincopyprint? JSONArray jsonArray = null;
JSONArray jsonArray = null;[java] view plaincopyprint? try {
try {
[java]
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jsonArray = JSONArray.fromObject(str);
jsonArray = JSONArray.fromObject(str);[java] view plaincopyprint? } catch (JSONException e) { e.printStackTrace(); }
} catch (JSONException e) { e.printStackTrace(); }
[java]
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return jsonArray; }
return jsonArray; }[java] view plaincopyprint? public static JSONObject StringToJSONOBject(String str) {
public static JSONObject StringToJSONOBject(String str) {
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if (str == null || str.trim().length() == 0)
if (str == null || str.trim().length() == 0)[java] view plaincopyprint? { return null; }
{ return null; }
[java]
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JSONObject jsonObject = null;
JSONObject jsonObject = null;[java] view plaincopyprint? try { jsonObject = JSONObject.fromObject(str);
try { jsonObject = JSONObject.fromObject(str);
[java]
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} catch (JSONException e) { e.printStackTrace(); }
} catch (JSONException e) { e.printStackTrace(); }
[java]
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return jsonObject; }}
return jsonObject; }}
3.新建一个Java类，名字叫做<strong><span style="color:#ff0000;">JsonConvert.java</span></strong>，同样打包到<span style="color:#ff0000;"><strong>young.ajax.json</strong></span>,将下面代码粘到里面。
<span style="color:#0000ff;">怎么样，这个看着更专业吧，但是你现在发现了，有好多的可修正的红叉叉啊，为什么哩？难道是类库？Bingo！需要好一大堆包啊。。哎！我观察了一下，我的里面有这么多包包，不排除有没用上的哈。</span>