通过codehaus来实现json写入文件和读取文件成json对象

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

>

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;

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public

class

JsonGeneratorAndParser
{

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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();

//
[

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035

jGenerator.writeString(

"msg
1"

);

//
"msg 1"

036

jGenerator.writeString(

"msg
2"

);

//
"msg 2"

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jGenerator.writeString(

"msg
3"

);

//
"msg 3"

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039

jGenerator.writeEndArray();

//
]

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041

jGenerator.writeEndObject();

//
}

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043

jGenerator.close();

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045

JsonParser
jParser = jfactory.createJsonParser(

new

File(

046

"c:/user.json"

));

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//
loop until token equal to "}"

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while

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

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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();

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

058

059

}

060

061

if

(

"age"

.equals(fieldname))
{

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//
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

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}

069

070

if

(

"messages"

.equals(fieldname))
{

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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

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}

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082

}

083

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}

085

jParser.close();

086

087

}

catch

(JsonGenerationException
e) {

088

089

e.printStackTrace();

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}

catch

(JsonMappingException
e) {

092

093

e.printStackTrace();

094

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}

catch

(IOException
e) {

096

097

e.printStackTrace();

098

099

}

100

101

}

102

}

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104