場景一

沒有頭的Json陣列
“e:/person”檔案內容如下，檔案中是沒有頭的json陣列

[
    {
        "id" : 1,
        "name" : "lzj",
        "age" : 27
    },
    {
        "id" : 2,
        "name" : "Bob",
        "age" : 20
    },
    {
        "id" : 3,
        "name" : "Terry",
        "age" : 26
    }
]

    /*也可用JsonReader來實現*/
 

    @Test
    public void test1() throws FileNotFoundException{
        GsonBuilder builder = new GsonBuilder();
        Gson gson = builder.create();
        FileReader fileReader = new FileReader("e:/person");
        JsonParser parser = new JsonParser();
        JsonElement jsonElement = parser.parse(fileReader);
        JsonArray asJsonArray = jsonElement.getAsJsonArray();
        List<Person> persons = new
 
 ArrayList<Person>();
        /*JsonArray繼承自JsonElement，JsonArray是JsonElement陣列形式*/
        for(JsonElement elment : asJsonArray){
            Person person = gson.fromJson(elment, Person.class);
            persons.add(person);
        }
        System.out.println(persons);
    }

執行程式，輸出如下：

[Person [id=1
 
, name=lzj, age=27], Person [id=2, name=Bob, age=20], Person [id=3, name=Terry, age=26]]

場景二

有頭的Json陣列
“e:/person1”檔案中json字串內容如下：

{
    "persons" :[
        {
            "id" : 1,
            "name" : "lzj",
            "age" : 27
        },
        {
            "id" : 2,
            "name" : "Bob",
            "age" : 20
        },
        {
            "id" : 3,
            "name" : "Terry",
            "age" : 26
        }
    ]

}

    @Test
    public void test2() throws FileNotFoundException{
        GsonBuilder builder = new GsonBuilder();
        Gson gson = builder.create();
        FileReader fileReader = new FileReader("e:/person1");
        JsonParser parser = new JsonParser();
        JsonElement jsonElement = parser.parse(fileReader);
        JsonObject jsonObject = jsonElement.getAsJsonObject();
        JsonArray jsonArray = jsonObject.getAsJsonArray("persons");
        List<Person> persons = new ArrayList<Person>();
        for(JsonElement elment : jsonArray){
            Person person = gson.fromJson(elment, Person.class);
            persons.add(person);
        }
        System.out.println(persons);
    }

執行程式，輸出如下

[Person [id=1, name=lzj, age=27], Person [id=2, name=Bob, age=20], Person [id=3, name=Terry, age=26]]

場景三

Json陣列外含有其他Json字串
“e:/person2”檔案中字串如下

{
    "code" : 200,
    "persons" :[
        {
            "id" : 1,
            "name" : "lzj",
            "age" : 27
        },
        {
            "id" : 2,
            "name" : "Bob",
            "age" : 20
        },
        {
            "id" : 3,
            "name" : "Terry",
            "age" : 26
        }
    ]

}

    @Test
    public void test3() throws FileNotFoundException{
        GsonBuilder builder = new GsonBuilder();
        Gson gson = builder.create();
        FileReader fileReader = new FileReader("e:/person2");
        Persons persons = gson.fromJson(fileReader, Persons.class);
        System.out.println(persons.getPersons());
    }

執行程式，輸出內容如下：

[Person [id=1, name=lzj, age=27], Person [id=2, name=Bob, age=20], Person [id=3, name=Terry, age=26]]

也可以用上一示例的方法進行解決，只是去獲取“persons”中的內容就可以了。場景二中的程式碼只需要把讀取的檔案修改為“e:/person2”,拿過來可以直接使用。

附：

public class Person {
    private int id;
    private String name;
    private int age;
    /*省略set/get/toString方法*/
}

public class Persons {
    private String code;
    private List<Person> persons;
    /*省略set/get/toString方法*/
}