Google Gson - 将给定的Json转换为Map中嵌套Map的数据结构

一、Json如下

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{
    "lbmember_hash": {
        "10.2.180.74:1300": {
            "protocol": "ANY",
            "opsState": "up",
            "ip": "10.2.180.74",
            "server": "10.2.180.74",
            "port": "1300"
        },
        "10.2.181.160": {
            "protocol": "ANY",
            "opsState": "up",
            "ip": "10.2.181.160",
            "server": "10.2.181.160",
            "port": "1119"
        }
    }
}

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二、定义对应的Java Bean

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/**
 * 
 */
package com.ebay.tools.cms.sync.model.lb;

/**
 * 
 * LBMember ResourceId: ip:port
 * 
 * @author Josh Wang(Sheng)
 * 
 * @email  [email protected]
 * 
 */
public class LBMemberSource extends LBSource {

	private static final long serialVersionUID = -3579858609342297799L;
	
	private String memberName; // ip:port - resource id

	private String ip;
	
	private String opsState;
	
	private int port;
	
	private String protocol;
	
	private String server;
	
	private String label;

	public String getIp() {
		return ip;
	}

	public void setIp(String ip) {
		this.ip = ip;
	}

	public String getOpsState() {
		return opsState;
	}

	public void setOpsState(String opsState) {
		this.opsState = opsState;
	}

	public int getPort() {
		return port;
	}

	public void setPort(int port) {
		this.port = port;
	}

	public String getProtocol() {
		return protocol;
	}

	public void setProtocol(String protocol) {
		this.protocol = protocol;
	}

	public String getServer() {
		return server;
	}

	public void setServer(String server) {
		this.server = server;
	}

	public String getLabel() {
		return label;
	}

	public void setLabel(String label) {
		this.label = label;
	}

	public String getMemberName() {
		return memberName;
	}

	public void setMemberName(String memberName) {
		this.memberName = memberName;
	}

	@Override
	public String toString() {
		return "LBMemberSource [memberName=" + memberName + ", ip=" + ip + ", opsState=" + opsState + ", port=" + port + ", protocol=" + protocol
				+ ", server=" + server + ", label=" + label + "]";
	}
	
	
	
}

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三、给出具体的转换类

/**
 * 
 */
package com.ebay.tools.cms.sync.utils;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Map;

import com.ebay.tools.cms.sync.model.SyncSource;
import com.ebay.tools.cms.sync.model.lb.LBMemberSource;
import com.google.common.reflect.TypeToken;
import com.google.gson.Gson;

/**
 * @author Josh Wang(Sheng)
 * 
 * @email  [email protected]
 * 
 */
public class GsonConverter<T extends SyncSource> {
	
	private Type genericType;
	
	public GsonConverter() {
		Type typeClass = getClass().getGenericSuperclass();
		genericType = ((ParameterizedType) typeClass).getActualTypeArguments()[0];
	}
	
	public static Map<String, String> json2Map(String jsonString) {
		Type type = new TypeToken<Map<String, String>>() {
			private static final long serialVersionUID = 1L;}.getType();
		Gson gson = new Gson();
		return gson.fromJson(jsonString, type);
	}
	
	public  Map<String, Map<String, LBMemberSource>> json2Maps(String jsonString) {
		Type typeToken = buildTypeToken(genericType);
		
		Gson gson = new Gson();
		return gson.fromJson(jsonString, typeToken);
	}
	
	private Type buildTypeToken(Type genericType) {
		Type typeToken = null;
		if (genericType.toString().endsWith(LBMemberSource.class.getSimpleName())) {
			typeToken = new TypeToken<Map<String, Map<String, LBMemberSource>>>() {
				private static final long serialVersionUID = 1L;}.getType();
		}
		
		return typeToken;
	}
	
}

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四、为便于测试，写一个IOUtils来读取上面的json文本，从而避免在测试用例中麻烦的输入Json文本

/**
 * 
 */
package com.ebay.tools.cms.sync.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;



/**
 * @author Josh Wang(Sheng)
 * 
 * @email  [email protected]
 * 
 */
public class IOUtils {

	public static String fileToString(String filePath) throws IOException {
		File file = new File(filePath);
		
		InputStream in = new FileInputStream(file);
		try {
			return org.apache.commons.io.IOUtils.toString(in);
		} finally {
			org.apache.commons.io.IOUtils.closeQuietly(in);
		}
	}

}

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五、最后给出测试类

/**
 * 
 */
package com.ebay.tools.cms.sync.util;


import java.io.IOException;



import java.util.Map;

import org.junit.Assert;
import org.junit.Test;

import com.ebay.tools.cms.sync.BaseTest;
import com.ebay.tools.cms.sync.model.lb.LBMemberSource;
import com.ebay.tools.cms.sync.utils.GsonConverter;
import com.ebay.tools.cms.sync.utils.IOUtils;

/**
 * @author Josh Wang(Sheng)
 * 
 * @email  [email protected]
 * 
 */
public class TestGsonConverter extends BaseTest {
	

	@Test
	public void json2Map() throws IOException {
		String lbmemberHashPath = "src/test/resources/lbmember_hash.txt";
		String hashString = IOUtils.fileToString(lbmemberHashPath);
		Assert.assertNotNull(hashString);
		
		Map<String, Map<String, LBMemberSource>> map = new GsonConverter<LBMemberSource>(){}.json2Maps(hashString);
		for (Map.Entry<String, Map<String, LBMemberSource>> entry : map.entrySet()) {
			printHighlight(entry.getKey());
			for (Map.Entry<String, LBMemberSource> entry2 : entry.getValue().entrySet()) {
				print(entry2.getValue().toString());
			}
		}
	}
	
}

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?本例中使用了Google Json中的TypeToken来获取具体泛型类的泛型参数类型，有关获取Java中泛型类的泛型参数类型，可参见另一篇博客：http://josh-persistence.iteye.com/blog/2165613

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