This blog introduces Jackson's features and how to use it
Jackson supports three ways to use
- Streaming API (Streaming API Incremental parsing/generation)
- Jsonparse reads, Jsongenerator writes
- Efficient
- Similar to the use of Part 1 JSON, it is not useful
- Tree-shaped model
- Objectmapper used to build and use with Jsonnode.
- Data binding
- JSON and Pojo convert each other
- Simple data conversion Simple object refers to the map in Java, list, etc.
- Full Data Conversion Custom JavaBean
User's perspective to evaluate these three methods of use
- Flow mode is the most efficient, fast, low memory consumption
- Data binding is the most convenient
- The most flexible tree-shaped model
Example:
Data binding examples
Json Javabean
User user = new user (); Javabeanobjectmapper mapper = new Objectmapper () Mapper.writevalue (New File ("/users/sangs/downloads/json.txt"), user); Write to File System.out.println (mapper.writevalueasstring (user));
Json-Javabean
Objectmapper mapper = new Objectmapper (); User user = Mapper.readvalue (new File ("/users/sangs/downloads/json.txt"), User.class); SYSTEM.OUT.PRINTLN (user);
The Javabean and JSON transformations are fairly simple and look intuitive, requiring only one converter objectmapper
Conversion of raw data to JSON
If we have the raw data, we want to be able to use the data directly into JSON, this JSON can be converted to JavaBean
Map<String, Object>UserData = new HashMap<String, Object>(); Map<String, String>namestruct = new HashMap<String, String>( ); Namestruct.put ("First", "Joe"), Namestruct.put ("Last", "Sixpack"), Userdata.put ("name", namestruct); Userdata.put ("Gender", "MALE"), Userdata.put ("verified", Boolean.false), Userdata.put ("Userimage", "rm9vymfyiq=="); Mapper.writevalue (New File ("User-modified.json"), userData);
Jackson Gson json.simple Part 2