Elasticsearch系列(八)----ES生成JSON与解析JSON的方式

雨点打透心脏的1/2处 2022-06-09 12:10 527阅读 0赞

**一、生成JSON**

四种方式如下,官网文档：[https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/java-docs-index.html][https_www.elastic.co_guide_en_elasticsearch_client_java-api_current_java-docs-index.html] :

**1.1手写方式生成**

String json = "{" +
    	"\"user\":\"fendo\"," +
    	"\"postDate\":\"2013-01-30\"," +
    	"\"message\":\"Hell word\"" +
    "}";

**1.2使用集合**

集合是key:value数据类型，可以代表json结构.

Map<String, Object> json = new HashMap<String, Object>();
    json.put("user","kimchy");
    json.put("postDate","2013-01-30");
    json.put("message","trying out Elasticsearch");

**1.3使用JACKSON序列化**

ElasticSearch已经使用了jackson，可以直接使用它把javabean转为json.

// instance a json mapper
    ObjectMapper mapper = new ObjectMapper(); // create once, reuse
    
    // generate json
    byte[] json = mapper.writeValueAsBytes(yourbeaninstance);

**1.4使用ElasticSearch 帮助类**

XContentBuilder builder = jsonBuilder()
    	.startObject()
    		.field("user", "kimchy")
    		.field("postDate", new Date())
    		.field("message", "trying out Elasticsearch")
    	.endObject()
    
     String json = builder.string();

完整示例:

package com.fendo.temp;
    
    import java.io.IOException;
    import java.net.InetAddress;
    import java.net.UnknownHostException;
    import java.util.Date;
    import java.util.HashMap;
    import java.util.Map;
    
    import org.elasticsearch.action.index.IndexResponse;
    import org.elasticsearch.client.transport.TransportClient;
    import org.elasticsearch.common.settings.Settings;
    import org.elasticsearch.common.transport.InetSocketTransportAddress;
    import org.elasticsearch.common.xcontent.XContentBuilder;
    import org.elasticsearch.common.xcontent.XContentFactory;
    import org.elasticsearch.transport.client.PreBuiltTransportClient;
    import org.junit.Before;
    import org.junit.Test;
    
    import com.fasterxml.jackson.core.JsonProcessingException;
    import com.fasterxml.jackson.databind.ObjectMapper;
    
    public class CreateIndex {
    
    	private TransportClient client;
    	
    	@Before
    	public void getClient() throws Exception{
            //设置集群名称
            Settings settings = Settings.builder().put("cluster.name", "my-application").build();// 集群名
            //创建client
            client  = new PreBuiltTransportClient(settings)
                    .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("127.0.0.1"), 9300));
    	}
    	
    	/**
    	 * 手动生成JSON
    	 */
    	@Test
    	public void CreateJSON(){
    		
    		String json = "{" +
    		        "\"user\":\"fendo\"," +
    		        "\"postDate\":\"2013-01-30\"," +
    		        "\"message\":\"Hell word\"" +
    		    "}";
    		
    		IndexResponse response = client.prepareIndex("fendo", "fendodate")
    		        .setSource(json)
    		        .get();
    		System.out.println(response.getResult());
    		
    	}
    	
    	
    	/**
    	 * 使用集合
    	 */
    	@Test
    	public void CreateList(){
    		
    		Map<String, Object> json = new HashMap<String, Object>();
    		json.put("user","kimchy");
    		json.put("postDate","2013-01-30");
    		json.put("message","trying out Elasticsearch");
    		
    		IndexResponse response = client.prepareIndex("fendo", "fendodate")
    		        .setSource(json)
    		        .get();
    		System.out.println(response.getResult());
    		
    	}
    	
    	/**
    	 * 使用JACKSON序列化
    	 * @throws Exception
    	 */
    	@Test
    	public void CreateJACKSON() throws Exception{
    		
    		CsdnBlog csdn=new CsdnBlog();
    		csdn.setAuthor("fendo");
    		csdn.setContent("这是JAVA书籍");
    		csdn.setTag("C");
    		csdn.setView("100");
    		csdn.setTitile("编程");
    		csdn.setDate(new Date().toString());
    		
    		// instance a json mapper
    		ObjectMapper mapper = new ObjectMapper(); // create once, reuse
    
    		// generate json
    		byte[] json = mapper.writeValueAsBytes(csdn);
    		
    		IndexResponse response = client.prepareIndex("fendo", "fendodate")
    		        .setSource(json)
    		        .get();
    		System.out.println(response.getResult());
    	}
    	
    	/**
    	 * 使用ElasticSearch 帮助类
    	 * @throws IOException 
    	 */
    	@Test
    	public void CreateXContentBuilder() throws IOException{
    		
    		XContentBuilder builder = XContentFactory.jsonBuilder()
    			    .startObject()
    			        .field("user", "ccse")
    			        .field("postDate", new Date())
    			        .field("message", "this is Elasticsearch")
    			    .endObject();
    		
            IndexResponse response = client.prepareIndex("fendo", "fendodata").setSource(builder).get();
            System.out.println("创建成功!");
            
    		
    	}
    	
    }

**二、解析JSON**

Jest对获取的JSON数据,有两种解析方式

1、手动解析

/**
         * 手动解析
         * @throws IOException 
         */
        @Test
        public void ManualOperation() throws IOException{
        	
        	int pageNumber=1;
        	int pageSize=10;
        	
        	SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        	searchSourceBuilder.query(QueryBuilders.queryStringQuery("JAVA"));
        	searchSourceBuilder.from((pageNumber - 1) * pageSize);//设置起始页
            searchSourceBuilder.size(pageSize);//设置页大小
            Search search = new Search.Builder(searchSourceBuilder.toString())
                    .addIndex(indexName)// 索引名称
                    .build();
            SearchResult result = jestClient.execute(search);
            
            
            
            // 手动解析
            JsonObject jsonObject = result.getJsonObject();
            JsonObject hitsobject = jsonObject.getAsJsonObject("hits");
            long took = jsonObject.get("took").getAsLong();
            long total = hitsobject.get("total").getAsLong();
            JsonArray jsonArray = hitsobject.getAsJsonArray("hits");
            
            System.out.println("took:"+took+"  "+"total:"+total);
            
            List<CsdnBlog> csdnBlogs=new ArrayList<CsdnBlog>(); 
            
            for (int i = 0; i < jsonArray.size(); i++) {
                JsonObject jsonHitsObject = jsonArray.get(i).getAsJsonObject();
    
                // 获取返回字段
                JsonObject sourceObject = jsonHitsObject.get("_source").getAsJsonObject();
    
                // 封装Article对象
                CsdnBlog article = new CsdnBlog();
                article.setTitile(sourceObject.get("titile").getAsString());
                article.setContent(sourceObject.get("content").getAsString());
                article.setAuthor(sourceObject.get("author").getAsString());
                article.setDate(sourceObject.get("date").getAsString());
                article.setTag(sourceObject.get("tag").getAsString());
                article.setView(sourceObject.get("view").getAsString());
                csdnBlogs.add(article);
                
          }
           
          System.out.println(csdnBlogs.size());
            
        }

2、自动解析:

/**
         * 自动解析
         * @throws Exception
         */
        @Test
        public void Auto() throws Exception{
        	
        	
        	int pageNumber=1;
        	int pageSize=10;
        	
        	SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        	searchSourceBuilder.query(QueryBuilders.queryStringQuery("JAVA"));
        	searchSourceBuilder.from((pageNumber - 1) * pageSize);//设置起始页
            searchSourceBuilder.size(pageSize);//设置页大小
            Search search = new Search.Builder(searchSourceBuilder.toString())
                    .addIndex(indexName)// 索引名称
                    .build();
            SearchResult result = jestClient.execute(search);
            
            
            // 自动解析
            JsonObject jsonObject = result.getJsonObject();
            JsonObject hitsobject = jsonObject.getAsJsonObject("hits");
            long took = jsonObject.get("took").getAsLong();
            long total = hitsobject.get("total").getAsLong();
            
            System.out.println("took:"+took+"  "+"total:"+total);
    
            
            List<SearchResult.Hit<CsdnBlog, Void>> hits = result.getHits(CsdnBlog.class);
            
            List<CsdnBlog> csdnBlogs=new ArrayList<CsdnBlog>(); 
            for (SearchResult.Hit<CsdnBlog, Void> hit : hits) {
            	
            	CsdnBlog source = hit.source;
            	csdnBlogs.add(source);
            	
            }
            System.out.println(csdnBlogs.size());
            
        }

[https_www.elastic.co_guide_en_elasticsearch_client_java-api_current_java-docs-index.html]: https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/java-docs-index.html