SSM報錯:No converter found for return value of type: class java.util.ArrayList at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageC
阿新 • • 發佈:2018-12-31
我使用的是SSM框架,是在編寫測試RESTFUL介面的時候出現,
@RequestMapping(value = "/selectAll", method = RequestMethod.GET) @ResponseBody public ResponseEntity<List<User>> selectAll() { List<User> users = this.userService.selectAll(); if (null != users && users.size() > 0) {return ResponseEntity.ok(users); } return ResponseEntity.status(HttpStatus.NOT_FOUND).body(null); }
程式碼不是非常嚴謹,只是做測試。
訪問:http://localhost:8081/selectAll
錯誤:
No converter found for return value of type: class java.util.ArrayList at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:187) at org.s
原因:這是因為springmvc預設是沒有物件轉換成json的轉換器的,需要手動新增jackson依賴。
解決:新增相關依賴
<!--jacson支援json--> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.5.4</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.5.4</version> </dependency>
成功解決:
[{"username":"admin","password":"admin"},{"username":"zhanxuewei","password":"123456"}]
參考:https://www.cnblogs.com/hafiz/p/5812873.html