jackson 完整Jar包

Jackson fasterxml和codehaus的区别： 他们是Jackson的两大分支、也是两个版本的不同包名。Jackson从2.0开始改用新的包名fasterxml；

1.x版本的包名是codehaus。除了包名不同，他们的Maven artifact id也不同。1.x版本现在只提供bug-fix，

2.x版本还在不断开发和发布中。如果是新项目，建议直接用2x，即fasterxml jackson。

P.S. Jackson可以轻松的将Java对象转换成json对象和xml文档，同样也可以将json、xml转换成Java对象。

官网：http://wiki.fasterxml.com/JacksonHome 三个主要的模块： jackson-co re：核心包 jackson-annotations：注解包 jackson-databind：数据绑定包 jackson-databind需要引用另外两个包，所以如果项目中需要jackson-databind，则只需要加入它的dependency就行了，其他两个会自动引入： <dependency> <groupId>com.fasterxml.jackson.

使用(java jar-jackson-all-1.9.0jar自行下载)

import java.io.StringWriter;  
import java.util.ArrayList;  
import java.util.HashMap;  
import java.util.List;  
import java.util.Map;  
  
import org.codehaus.jackson.JsonFactory;  
import org.codehaus.jackson.JsonGenerator;  
import org.codehaus.jackson.JsonParser;  
import org.codehaus.jackson.map.DeserializationConfig.Feature;  
import org.codehaus.jackson.map.MappingJsonFactory;  
import org.codehaus.jackson.map.ObjectMapper;  
import org.codehaus.jackson.type.JavaType;  
  
public class JsonUtils {  
  
    public static <K, V> String toJson(Map<K, V> obj) {  
        String jsonString = "";  
        try {  
            if (obj == null) {  
                return "";  
            }  
            StringWriter sw = new StringWriter();  
            JsonGenerator gen = new JsonFactory().createJsonGenerator(sw);  
            ObjectMapper mapper = new ObjectMapper();  
            mapper.writeValue(gen, obj);  
            jsonString = sw.toString();  
            sw.close();  
        } catch (Exception ex) {  
            ex.printStackTrace();  
            return "";  
        }  
  
        return jsonString;  
    }  
  
    @SuppressWarnings("unchecked")  
    public static Map<String, Object> toMap(String json) {  
        Map<String, Object> result = new HashMap<String, Object>();  
        try {  
            if (json == null || json.equals("")) {  
                return null;  
            }  
  
            ObjectMapper objectMapper = new ObjectMapper();  
            result = objectMapper.readValue(json, Map.class);  
            if (result == null) {  
                return new HashMap<String, Object>();  
            }  
        } catch (Exception ex) {  
            ex.printStackTrace();  
        }  
  
        return result;  
    }  
  
    public static String toJson(Object object) {  
        String json = "";  
        try {  
            if (object == null) {  
                return "";  
            }  
            StringWriter sw = new StringWriter();  
            JsonGenerator gen = new JsonFactory().createJsonGenerator(sw);  
            ObjectMapper mapper = new ObjectMapper();  
  
            mapper.writeValue(gen, object);  
  
            json = sw.toString();  
            sw.close();  
        } catch (Exception ex) {  
            ex.printStackTrace();  
            json = "";  
        }  
        return json;  
    }  
  
    public static <T> T toObject(String json, Class<T> clazz) {  
        T obj = null;  
        try {  
            if (json == null || json.equals("")) {  
                return null;  
            }  
            JsonFactory jsonFactory = new MappingJsonFactory();  
            JsonParser jsonParser = jsonFactory.createJsonParser(json);  
            ObjectMapper mapper = new ObjectMapper();  
    mapper.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES,false);
            //mapper.getDeserializationConfig().set(Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);  
            obj = mapper.readValue(jsonParser, clazz);  
  
        } catch (Exception ex) {  
            ex.printStackTrace();  
            obj = null;  
        }  
        return obj;  
  
    }  
  
    public static <T> List<T> toList(String json, Class<T> clazz) {  
        if (json == null || json.equals("")) {  
            return null;  
        }  
        ObjectMapper mapper = new ObjectMapper();  
        mapper.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES,false); 
        List<T> list = new ArrayList<T>();  
        try {  
            JavaType type = mapper.getTypeFactory().constructParametricType(List.class, clazz);  
            list = mapper.readValue(json, type);  
            return list;  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
  
        return list;  
    }  
}