Java Server Pages - collation when inserting into MySql?

问题

I am using Java Server Pages and got problem with collation when inserting data from my application. My insert code looks like this:

<%@page import="java.sql.*" %>
  <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
    <% Class.forName( "com.mysql.jdbc.Driver"); 
       Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/myapp", "root", ""); 
       Statement st=con.createStatement(); 
       ResultSet rs; 
       st.executeUpdate("insert into table values (default,1,2,šđžćč)"); %>

In my database result looks like this š?ž?? (so he can see understand 2 letters but not all). How to fix it so all letters will be in my database?

EDIT : I can insert data with those characters via phpmyadmin, but i can't from .jsp file to database. It's like charset = utf-8 on my jsp file is not working.

回答1:

Question marks come from this:

The client has a valid character (good), and
The SET NAMES agrees with the encoding that the client has (good), but
The target column's CHARACTER SET does not include the intended character (bad).

Examples:

latin1 handles only Western European characters; trying to put an Eastern European character or any Asian character in it won't fit.
latin2 and cp1250 can handle Czech, so conversions between them are mostly OK, but not between either of them and latin1
utf8mb4 is a superset of utf8. Putting a utf8 character into utf8mb4 is ok, but the reverse will result in a '?' in some cases.

The characters that were converted to '?' can not be recovered from the table.

How to fix future INSERTs?

Using utf8mb4 on the table column(s) probably works in all cases.
Otherwise, pick some CHARACTER SET for the table column(s) that reasonably matches the client data.

The reason for only some of the characters being ? (in š?ž??) is because šž exist in latin1 but the others do not.

Bottom line: Change the CHARACTER SET in the table definition.

回答2:

Problem solved with adding to my connection from old path

Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/myapp", "root", "");

Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/myapp?useUnicode=true&characterEncoding=UTF-8", "root", "");

来源：https://stackoverflow.com/questions/31700235/java-server-pages-collation-when-inserting-into-mysql

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java

mysql

jsp

collation