10 2020 档案
摘要：一.最原始的使用jdbc连接mysql: maven依赖只要一个： <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.45</version> </depe
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摘要：public class A { private A1 a1; public A1 getA1() { return a1; } public void setA1(A1 a1) { this.a1 = a1; } } public class A1 { private A2 a2; public
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