jackson 生成 json 字符串示例

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.Test;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class JackSonTest {
    @Test
    public void buildJson() throws IOException {
        JsonFactory jsonFactory = new JsonFactory();
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        JsonGenerator generator = jsonFactory.createGenerator(byteArrayOutputStream);

        generator.writeStartObject();
        generator.writeBooleanField("isBoolean", true);
        generator.writeStringField("String", "value");
        generator.writeNumberField("number", 2);

        generator.writeArrayFieldStart("array");
        ObjectMapper objectMapper = new ObjectMapper();
        Map map = new HashMap<>(2);
        map.put("key1", "value1");
        map.put("key2", "value2");
        for (int i = 0; i < 2; i++) {
            objectMapper.writevalue(generator, map);
        }
        generator.writeEndArray();

        generator.writeEndObject();

        generator.flush();
        generator.close();

        System.out.println(byteArrayOutputStream);
    }
}

{
    "isBoolean":true,
    "String":"value",
    "number":2,
    "array":[
        {
            "key1":"value1",
            "key2":"value2"
        },
        {
            "key1":"value1",
            "key2":"value2"
        }
    ]
}