mirror of https://github.com/alibaba/fastjson2.git
212 lines
3.7 KiB
Markdown
212 lines
3.7 KiB
Markdown
# 1. Prepare
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If your project uses `kotlin`, you can use the` Fastjson-Kotlin` module, and use the characteristics of `kotlin`.
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### 1.1 Download
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`Maven`:
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```xml
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<dependency>
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<groupId>com.alibaba.fastjson2</groupId>
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<artifactId>fastjson2-kotlin</artifactId>
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<version>2.0.8</version>
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</dependency>
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```
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`Kotlin Gradle`:
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```kotlin
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dependencies {
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implementation("com.alibaba.fastjson2:fastjson2-kotlin:2.0.8")
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}
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```
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### 1.2 Import functions
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Whenever the function in the `Fastjson-Kotlin`, you need to complete the import functions work, **otherwise it will be prompted that the corresponding function will not be found**.
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E.g:
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```kotlin
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import com.alibaba.fastjson2.to
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import com.alibaba.fastjson2.into
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```
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If you use a lot of functions, you can use batch import.
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```kotlin
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import com.alibaba.fastjson2.*
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```
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# 2. Usage
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We have unified function names `to` and` into`.
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- Use `to` to use `::class.java`, suitable for categories without generic Class.
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- Use `into` to use the `TypeReference`, which is suitable for genetic Class.
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First define a User class
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```kotlin
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class User(
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var id: Int,
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var name: String
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)
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```
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### 2.1 Parse `JSON` into `JSONObject`
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```kotlin
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val text = "..." // String
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val data = text.parseObject()
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val bytes = ... // ByteArray
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val data = bytes.parseObject() // JSONObject
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```
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### 2.2 Parse `JSON` into `JSONArray`
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`Kotlin`:
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```kotlin
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val text = "..." // String
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val data = text.parseArray() // JSONArray
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```
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### 2.2 Create the `Typereference` of specified Class
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```kotlin
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val refer = reference<User>()
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```
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### 2.3 Parse `JSON` into an Object
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No generic:
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```kotlin
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val text = "..." // String
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val data = text.to<User>() // User
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```
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Including generic:
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```kotlin
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val text = "..." // String
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val data = text.into<List<User>>() // List<User>
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val data = text.into<Map<String, User>>() // Map<String, User>
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```
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### 2.4 Serialization Object to `JSON`
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Serialization as a string:
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```kotlin
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val data = "..." // Any
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val text = text.toJSONString() // String
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```
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Serialization as a ByteArray:
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```kotlin
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val data = "..." // Any
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val bytes = text.toJSONByteArray() // ByteArray
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```
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### 2.5 Use `JSONObject`、`JSONArray`
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#### 2.5.1 Get simple property
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```kotlin
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val text = "..."
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val data = JSON.parseObject(text) // JSONObject
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val id = data.getIntValue("id") // Int
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val name = data.getString("name") // String
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```
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#### 2.5.2 Get Bean Object
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No generic:
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```kotlin
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val obj = ... // JSONObject
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val array = ... // JSONArray
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val user = array.to<User>(0)
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val user = obj.to<User>("key")
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```
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Including generic:
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```kotlin
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val obj = ... // JSONObject
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val array = ... // JSONArray
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val user = array.into<List<User>>(0)
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val user = obj.into<List<User>>("key")
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```
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#### 2.5.3 Convert to Bean Object
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No generic:
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```kotlin
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val obj = ... // JSONObject
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val array = ... // JSONArray
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val user = obj.to<User>() // User
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val users = array.toList<User>() // List<User>
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```
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Including generic:
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```kotlin
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val obj = ... // JSONObject
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val array = ... // JSONArray
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val user = obj.into<HashMap<String, User>>() // HashMap<String, User>
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val users = array.into<ArrayList<User>>() // ArrayList<User>
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```
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### 2.5 Convert `URL`、`InputStream` to Bean Object
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No generic:
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```kotlin
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val url = ... // URL
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val data = url.to<User>()
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```
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```kotlin
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val input = ... // InputStream
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val data = input.to<User>()
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```
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Including generic:
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```kotlin
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val url = ... // URL
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val data = url.into<List<User>>()
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```
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```kotlin
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val input = ... // InputStream
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val data = input.into<List<User>>()
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```
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# 3. Advanced usage
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### 3.1 Use `JSONPath`
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#### 3.1.1 Use `JSONPath` to read specified data
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```kotlin
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val text = "..."
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val path = "$.id".toPath() // JSONPath
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val parser = JSONReader.of(text)
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val result = path.extract(parser)
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```
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