移动架构-json解析框架

JSON在现在数据传输中占据着重要地位，相比于xml，其解析和构成都要简单很多，第三方的解析框架也不胜枚举，这里之所以要自定义一个json解析框架，一方面是更好的了解json解析过程，另一方面是有时候需要对解析出来的json数据做转换

实现的功能

json转model，model转json

实现代码

转化类

public class FastJson {
    public static final int JSON_ARRAY = 1;
    public static final int JSON_OBJECT = 2;
    public static final int JSON_ERRO = 3;

    //调用层调用
    public static Object pareseObject(String json, Class clazz) {
        Object object = null;
        Class<?> jsonClass = null;
        //JSONArray类型
        if (json.charAt(0) == '[') {
            try {
                object = toList(json, clazz);
            } catch (JSONException e) {
                e.printStackTrace();
            }
        } else if (json.charAt(0) == '{') {
            try {
                JSONObject jsonObject = new JSONObject(json);
                //反射得到最外层的model
                object = clazz.newInstance();
                //得到的最外层的key集合
                Iterator<?> iterator = jsonObject.keys();
                //遍历集合
                while (iterator.hasNext()) {
                    String key = (String) iterator.next();
                    Object fieldValue = null;
                    //得到当前clazz类型的所有成员变量
                    List<Field> fields = getAllFields(clazz, null);
                    for (Field field : fields) {
                        //将key和成员变量进行匹配
                        if (field.getName().equalsIgnoreCase(key)) {
                            field.setAccessible(true);
                            //得到key所对应的值
                            fieldValue = getFieldValue(field, jsonObject, key);
                            if (fieldValue != null) {
                                field.set(object, fieldValue);
                            }
                            field.setAccessible(false);
                        }
                    }
                }
            } catch (JSONException e) {
                e.printStackTrace();
            } catch (InstantiationException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return object;
    }

    //得到当前的value值
    private static Object getFieldValue(Field field, JSONObject jsonObject, String key) throws JSONException {
        Object fieldValue = null;
        //得到当前成员变量类型
        Class<?> fieldClass = field.getType();
        if (fieldClass.getSimpleName().toString().equals("int")
                || fieldClass.getSimpleName().toString().equals("Integer")) {
            fieldValue = jsonObject.getInt(key);
        } else if (fieldClass.getSimpleName().toString().equals("double")
                || fieldClass.getSimpleName().toString().equals("Double")) {
            fieldValue = jsonObject.getDouble(key);
        } else if (fieldClass.getSimpleName().toString().equals("boolean")
                || fieldClass.getSimpleName().toString().equals("Boolean")) {
            fieldValue = jsonObject.getBoolean(key);
        } else if (fieldClass.getSimpleName().toString().equals("long")
                || fieldClass.getSimpleName().toString().equals("Long")) {
            fieldValue = jsonObject.getLong(key);
        } else if (fieldClass.getSimpleName().toString().equals("String")) {
            fieldValue = jsonObject.getString(key);
        } else {
            //判断集合类型和对象类型
            String jsonValue = jsonObject.getString(key);
            switch (getJSONType(jsonValue)) {
                case JSON_ARRAY:
                    Type fieldType = field.getGenericType();
                    if (fieldType instanceof ParameterizedType) {
                        ParameterizedType parameterizedType = (ParameterizedType) fieldType;
                        //当前类所实现的泛型
                        Type[] fieldArgType = parameterizedType.getActualTypeArguments();
                        for (Type type : fieldArgType) {
                            Class<?> fieldArgClass = (Class<?>) type;
                            fieldValue = toList(jsonValue, fieldArgClass);
                        }
                    }
                    break;
                case JSON_OBJECT:
                    //fieldClass成员变量类型
                    fieldValue = pareseObject(jsonValue, fieldClass);
                    break;
                case JSON_ERRO:
                    break;
            }
        }
        return fieldValue;
    }

    //获取当前json字符串的类型
    private static int getJSONType(String jsonValue) {
        char firstChar = jsonValue.charAt(0);
        if (firstChar == '{') {
            return JSON_OBJECT;
        } else if (firstChar == '[') {
            return JSON_ARRAY;
        } else {
            return JSON_ERRO;
        }
    }

    //解析JsonArray数组
    private static Object toList(String json, Class clazz) throws JSONException {
        List<Object> list = null;
        JSONArray jsonArray = new JSONArray(json);
        list = new ArrayList<>();
        for (int i = 0; i < jsonArray.length(); i++) {
            //拿到JSON字符串
            String jsonValue = jsonArray.getJSONObject(i).toString();
            switch (getJSONType(jsonValue)) {
                case JSON_ARRAY:
                    //外层JSONArray嵌套里面JSONArray
                    List<?> infoList = (List<?>) toList(jsonValue, clazz);
                    list.add(infoList);
                    break;
                case JSON_OBJECT:
                    list.add(pareseObject(jsonValue, clazz));
                    break;
                case JSON_ERRO:
                    break;
            }
        }
        return list;
    }

    public static String toJson(Object object) {
        //JSON载体
        StringBuilder jsonBuilder = new StringBuilder();
        //判断是否是集合类型
        if (object instanceof List<?>) {
            jsonBuilder.append("[");
            List<?> list = (List<?>) object;
            //获取集合类型
            for (int i = 0; i < list.size(); i++) {
                //解析成JSONObject类型
                addObjectToJson(jsonBuilder, list.get(i));
                if (i < list.size() - 1) {
                    jsonBuilder.append(",");
                }
            }
        } else {
            addObjectToJson(jsonBuilder, object);
        }
        return jsonBuilder.toString();
    }

    //解析单独的JSONObject类型
    private static void addObjectToJson(StringBuilder jsonBuilder, Object o) {
        jsonBuilder.append("{");
        List<Field> fields = new ArrayList<>();
        getAllFields(o.getClass(), fields);
        for (int i = 0; i < fields.size(); i++) {
            //代表get方法
            Method method = null;
            Field field = fields.get(i);
            String fieldName = field.getName();
            Object fieldValue = null;
            //get类型方法
            String methodName = "get" + ((char) (fieldName.charAt(0) - 0x20) + fieldName.substring(1));
            try {
                //得到method对象
                method = o.getClass().getMethod(methodName);
            } catch (NoSuchMethodException e) {
                //is类型方法
                methodName = "is" + ((char) (fieldName.charAt(0) - 0x20) + fieldName.substring(1));
                try {
                    method = o.getClass().getMethod(methodName);
                } catch (NoSuchMethodException e1) {
                }
            }
            if (method != null) {
                try {
                    fieldValue = method.invoke(o);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            if (fieldValue != null) {
                jsonBuilder.append("\"");
                jsonBuilder.append(fieldName);
                jsonBuilder.append("\":");
                if (fieldValue instanceof Integer
                        || fieldValue instanceof Double
                        || fieldValue instanceof Long
                        || fieldValue instanceof Boolean) {
                    jsonBuilder.append(fieldValue.toString());
                } else if (fieldValue instanceof String) {
                    jsonBuilder.append("\"");
                    jsonBuilder.append(fieldValue.toString());
                    jsonBuilder.append("\"");
                } else if (fieldValue instanceof List<?>) {
                    addListToBuffer(jsonBuilder, fieldValue);
                } else {
                    //类类型
                    addObjectToJson(jsonBuilder, fieldValue);
                }
                jsonBuilder.append(",");
            }
            if (i == fields.size() - 1 && jsonBuilder.charAt(jsonBuilder.length() - 1) == ',') {
                jsonBuilder.deleteCharAt(jsonBuilder.length() - 1);
            }
        }
        jsonBuilder.append("}");
    }

    //解析集合类型数据
    private static void addListToBuffer(StringBuilder jsonBuilder, Object fieldValue) {
        List<?> list = (List<?>) fieldValue;
        jsonBuilder.append("[");
        for (int i = 0; i < list.size(); i++) {
            addObjectToJson(jsonBuilder, list.get(i));
            if (i < list.size() - 1) {
                jsonBuilder.append(",");
            }
        }
        jsonBuilder.append("]");
    }

    //获取当前Class所有成员变量
    private static List<Field> getAllFields(Class<?> aClass, List<Field> fields) {
        if (fields == null) {
            fields = new ArrayList<>();
        }
        //排除Object类型
        if (aClass.getSuperclass() != null) {
            //拿到当前Class的所有成员变量的Field
            Field[] fieldsSelf = aClass.getDeclaredFields();
            for (Field field : fieldsSelf) {
                //排除final修饰的成员变量
                if (!Modifier.isFinal(field.getModifiers())) {
                    fields.add(field);
                }
            }
            getAllFields(aClass.getSuperclass(), fields);
        }
        return fields;
    }
}

测试的model类

public class News {
    private int id;
    private String title;
    private String content;
    private User author;
    private boolean isCancle;
    private List<User> reader;

    public News() {
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public User getAuthor() {
        return author;
    }

    public void setAuthor(User author) {
        this.author = author;
    }

    public boolean isCancle() {
        return isCancle;
    }

    public void setCancle(boolean cancle) {
        isCancle = cancle;
    }

    public List<User> getReader() {
        return reader;
    }

    public void setReader(List<User> reader) {
        this.reader = reader;
    }

    @Override
    public String toString() {
        return "News [id=" + id + ", title=" + title + ", content=" + content
                + ", author=" + author + ", isCancle=" + isCancle + ", reader=" + reader + "]";
    }
}

public class User {
    private int id;
    private String name;
    private String password;

    public User() {
    }

    public User(int id, String name, String password) {
        this.id = id;
        this.name = name;
        this.password = password;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", password=" + password + "]";
    }
}

调用测试

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private News news;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.text_view);
    }

    public void modelToJson(View view) {
        setNews();
        String json = FastJson.toJson(news);
        textView.append(json);
        textView.append("\n\n");
    }

    public void jsonToModel(View view) {
        String json = FastJson.toJson(news);
        News news = (News) FastJson.pareseObject(json, News.class);
        textView.append(news.toString());
        textView.append("\n\n");
    }

    public void cleanText(View view) {
        textView.setText("");
    }

    private void setNews(){
        news = new News();
        news.setId(1);
        news.setTitle("Test Title");
        news.setContent("Test Content");
        news.setCancle(true);
        news.setAuthor(createAuthor());
        news.setReader(createReaders());
    }

    private static List<User> createReaders() {
        List<User> readers = new ArrayList<User>();
        User readerA = new User();
        readerA.setId(2);
        readerA.setName("Jack");
        readers.add(readerA);
        User readerB = new User();
        readerB.setId(1);
        readerB.setName("Bob");
        readerB.setPassword("123456");
        readers.add(readerB);
        return readers;
    }

    private static User createAuthor() {
        User author = new User();
        author.setId(1);
        author.setName("Alen");
        author.setPassword("123456");
        return author;
    }
}

测试结果如图所示