通过codehaus来实现json写入文件和读取文件成json对象

首先:pom.xml需要增加依赖，如下：

01 <dependency>
02 <groupId>org.codehaus.jackson</groupId>
03 <artifactId>jackson-core-lgpl</artifactId>
04 <version>1.9.1</version>
05 </dependency>
06 <dependency>
07 <groupId>org.codehaus.jackson</groupId>
08 <artifactId>jackson-mapper-lgpl</artifactId>
09 <version>1.9.1</version>
10 </dependency>

具体的demo，如下：

001	package com.javaniu.json;

002

003	import java.io.File;

004	import java.io.IOException;

005

006	import org.codehaus.jackson.JsonEncoding;

007	import org.codehaus.jackson.JsonFactory;

008	import org.codehaus.jackson.JsonGenerationException;

009	import org.codehaus.jackson.JsonGenerator;

010	import org.codehaus.jackson.JsonParser;

011	import org.codehaus.jackson.JsonToken;

012	import org.codehaus.jackson.map.JsonMappingException;

013

014	public class JsonGeneratorAndParser {

015

016

/**

017	* @param args

018

*/

019	public static void main(String[] args) {

020

try {

021

022	JsonFactory jfactory = new JsonFactory();

023

024	/*** write to file ***/

025	JsonGenerator jGenerator = jfactory.createJsonGenerator(new File(

026	"c:/user.json"), JsonEncoding.UTF8);

027	jGenerator.writeStartObject(); // {

028

029	jGenerator.writeStringField("name", "java牛"); // "name" : "java牛"

030	jGenerator.writeNumberField("age", 29); // "age" : 29

031

032	jGenerator.writeFieldName("messages"); // "messages" :

033	jGenerator.writeStartArray(); // [

034

035	jGenerator.writeString("msg 1"); // "msg 1"

036	jGenerator.writeString("msg 2"); // "msg 2"

037	jGenerator.writeString("msg 3"); // "msg 3"

038

039	jGenerator.writeEndArray(); // ]

040

041	jGenerator.writeEndObject(); // }

042

043	jGenerator.close();

044

045	JsonParser jParser = jfactory.createJsonParser(new File(

046	"c:/user.json"));

047

048	// loop until token equal to "}"

049	while (jParser.nextToken() != JsonToken.END_OBJECT) {

050

051	String fieldname = jParser.getCurrentName();

052	if ("name".equals(fieldname)) {

053

054	// current token is "name",

055	// move to next, which is "name"'s value

056	jParser.nextToken();

057	System.out.println(jParser.getText());

058

059

}

060

061	if ("age".equals(fieldname)) {

062

063	// current token is "age",

064	// move to next, which is "name"'s value

065	jParser.nextToken();

066	System.out.println(jParser.getIntValue()); // display 29

067

068

}

069

070	if ("messages".equals(fieldname)) {

071

072	jParser.nextToken(); // current token is "[", move next

073

074	// messages is array, loop until token equal to "]"

075	while (jParser.nextToken() != JsonToken.END_ARRAY) {

076

077	// display msg1, msg2, msg3

078	System.out.println(jParser.getText());

079

080

}

081

082

}

083

084

}

085	jParser.close();

086

087	} catch (JsonGenerationException e) {

088

089	e.printStackTrace();

090

091	} catch (JsonMappingException e) {

092

093	e.printStackTrace();

094

095	} catch (IOException e) {

096

097	e.printStackTrace();

098

099

}

100

101

}

102

}

103

104

源码下载： http://www.zuidaima.com/share/1550463256562688.htm