如何使用jackson反序列化json到对象

写个完整的，供你参考：
[code="java"]
import java.util.List;

import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.map.ObjectMapper;

public class TestJackson {
private static String json = "{\"indexs\":[{\"id\":\"6310_2\",\"createTime\":1359424596001,\"indexFields\":[{\"name\":\"keyword_score\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"2.1781344\",\"longValue\":0,\"intValue\":0},{\"name\":\"object_id\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"6310\",\"longValue\":0,\"intValue\":0},{\"name\":\"object_type\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"2\",\"longValue\":0,\"intValue\":0},{\"name\":\"user_id\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"657\",\"longValue\":0,\"intValue\":0},{\"name\":\"user_name\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"好书推荐\",\"longValue\":0,\"intValue\":0},{\"name\":\"publish_time\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"1324892396000\",\"longValue\":0,\"intValue\":0},{\"name\":\"name\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"水浒传\",\"longValue\":0,\"intValue\":0}]}]}";

/**
 * @param args
 */
public static void main(String[] args) throws Exception {
    ObjectMapper mapper = new ObjectMapper(); 
    JsonNode jsonNode = mapper.readTree(json); 
    JsonNode jn = jsonNode.get("indexs");
    System.out.println(jn.toString());

    Index p = mapper.readValue(json, Index.class); 
    System.out.println(p.getIndexs());
    List<Model> indexs = p.getIndexs();
    for(Model m : indexs) {
        System.out.println(m.getId());
    }
}

}

class Index {
private List indexs;

public List<Model> getIndexs() {
    return indexs;
}

public void setIndexs(List<Model> indexs) {
    this.indexs = indexs;
}

}

class Model {
private String id;
private long createTime;
private List indexFields;
public Model() {

}
public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}
public long getCreateTime() {
    return createTime;
}
public void setCreateTime(long createTime) {
    this.createTime = createTime;
}
public List<Field> getIndexFields() {
    return indexFields;
}
public void setIndexFields(List<Field> indexFields) {
    this.indexFields = indexFields;
}

}

class Field {
private String name;
private int type;
private boolean analyzed;
private boolean highlight;
private String strValue;
private long longValue;
private int intValue;

public Field() {

}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public int getType() {
    return type;
}
public void setType(int type) {
    this.type = type;
}
public boolean isAnalyzed() {
    return analyzed;
}
public void setAnalyzed(boolean analyzed) {
    this.analyzed = analyzed;
}
public boolean isHighlight() {
    return highlight;
}
public void setHighlight(boolean highlight) {
    this.highlight = highlight;
}
public String getStrValue() {
    return strValue;
}
public void setStrValue(String strValue) {
    this.strValue = strValue;
}
public long getLongValue() {
    return longValue;
}
public void setLongValue(long longValue) {
    this.longValue = longValue;
}
public int getIntValue() {
    return intValue;
}
public void setIntValue(int intValue) {
    this.intValue = intValue;
}

}
[/code]

[code="java"]
String personstr = getRequest().getParameter("persons");
JSONArray json = JSONArray.fromObject(personstr);
List persons = (List)JSONArray.toCollection(json, nvoidPerson.class);

[/code]，[url]http://blog.sina.com.cn/s/blog_5920510a01011vu8.html[/url]

给你写个简单的例子，仅供参考：
[code="java"]
import java.util.List;

import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;

public class TestJackson {
private static String json = "{\"indexs\":[{\"id\":\"6310_2\",\"createTime\":1359424596001,\"indexFields\":[{\"name\":\"keyword_score\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"2.1781344\",\"longValue\":0,\"intValue\":0},{\"name\":\"object_id\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"6310\",\"longValue\":0,\"intValue\":0},{\"name\":\"object_type\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"2\",\"longValue\":0,\"intValue\":0},{\"name\":\"user_id\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"657\",\"longValue\":0,\"intValue\":0},{\"name\":\"user_name\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"好书推荐\",\"longValue\":0,\"intValue\":0},{\"name\":\"publish_time\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"1324892396000\",\"longValue\":0,\"intValue\":0},{\"name\":\"name\",\"type\":1,\"analyzed\":true,\"highlight\":true,\"strValue\":\"水浒传\",\"longValue\":0,\"intValue\":0}]}]}";

/**
 * @param args
 */
public static void main(String[] args) throws Exception {
    ObjectMapper mapper = new ObjectMapper(); 
    JsonNode jsonNode = mapper.readTree(json); 
    //JsonNode jn = jsonNode.get("indexs");
    String id = jsonNode.get("indexs").toString(); 
    System.out.println(id);
    //List list =  mapper.readValue(person, new TypeReference<List>() {
    //}); 
    //Person p = mapper.readValue(person,Person.class); 
}

}
[/code]

jackson主要使用下面两段代码完成反序列化话：
[code="java"]
ObjectMapper mapper = new ObjectMapper();
JsonNode jsonNode = mapper.readTree(json); //json为json字符串
[/code]
然后通过jsonNode再做相应的处理。如对于对象转换，直接使用
Person p = mapper.readValue(person,Person.class);

如果对于List类型，使用：
[code="java"]
List list = mapper.readValue(person, new TypeReference() {
});
[/code]