sqlCommand 源码

docs/Mybatis/HuiFer-Mybatis-SqlCommand.md

@@ -0,0 +1,101 @@
+# sqlCommand 
+- `org.apache.ibatis.binding.MapperMethod.SqlCommand`
+```java
+    /**
+     * 核心内容: sql id , Sql 类型
+     */
+    public static class SqlCommand {
+
+        /**
+         * sql id
+         */
+        private final String name;
+        /**
+         * sql  类型select|update|delete|insert|...
+         */
+        private final SqlCommandType type;
+
+        /**
+         * 根据传递的参数 设置sql的一些属性 , sql id , type .
+         *
+         * @param configuration
+         * @param mapperInterface
+         * @param method
+         */
+        public SqlCommand(Configuration configuration, Class<?> mapperInterface, Method method) {
+            // 方法名
+            final String methodName = method.getName();
+            final Class<?> declaringClass = method.getDeclaringClass();
+            // Statement 实质是sql
+            MappedStatement ms = resolveMappedStatement(mapperInterface, methodName, declaringClass,
+                    configuration);
+            if (ms == null) {
+                if (method.getAnnotation(Flush.class) != null) {
+                    name = null;
+                    type = SqlCommandType.FLUSH;
+                } else {
+                    throw new BindingException("Invalid bound statement (not found): "
+                            + mapperInterface.getName() + "." + methodName);
+                }
+            } else {
+                name = ms.getId();
+                type = ms.getSqlCommandType();
+                if (type == SqlCommandType.UNKNOWN) {
+                    throw new BindingException("Unknown execution method for: " + name);
+                }
+            }
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public SqlCommandType getType() {
+            return type;
+        }
+
+        /**
+         * @param mapperInterface mapper.class
+         * @param methodName      方法名
+         * @param declaringClass  可能是 mapper.class
+         * @param configuration
+         * @return
+         */
+        private MappedStatement resolveMappedStatement(Class<?> mapperInterface, String methodName,
+                                                       Class<?> declaringClass, Configuration configuration) {
+//            接口名称+方法名
+            String statementId = mapperInterface.getName() + "." + methodName;
+            if (configuration.hasStatement(statementId)) {
+                // 从 configuration 获取
+                return configuration.getMappedStatement(statementId);
+            } else if (mapperInterface.equals(declaringClass)) {
+                return null;
+            }
+
+            // new 一个新的实例
+            for (Class<?> superInterface : mapperInterface.getInterfaces()) {
+                if (declaringClass.isAssignableFrom(superInterface)) {
+                    MappedStatement ms = resolveMappedStatement(superInterface, methodName,
+                            declaringClass, configuration);
+                    if (ms != null) {
+                        return ms;
+                    }
+                }
+            }
+            return null;
+        }
+    }
+
+```
+
+
+![image-20191218191512184](/images/mybatis/image-20191218191512184.png)
+
+
+
+![image-20191218191550550](/images/mybatis/image-20191218191550550.png)
+
+
+
+
+