EqualsHashCodePlugin.java
/*
* Copyright 2006-2026 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.mybatis.generator.plugins;
import static org.mybatis.generator.internal.util.JavaBeansUtil.getGetterMethodName;
import static org.mybatis.generator.internal.util.StringUtility.isTrue;
import java.util.Iterator;
import java.util.List;
import java.util.Properties;
import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.PluginAdapter;
import org.mybatis.generator.api.dom.OutputUtilities;
import org.mybatis.generator.api.dom.java.FullyQualifiedJavaType;
import org.mybatis.generator.api.dom.java.JavaVisibility;
import org.mybatis.generator.api.dom.java.Method;
import org.mybatis.generator.api.dom.java.Parameter;
import org.mybatis.generator.api.dom.java.TopLevelClass;
/**
* This plugin adds equals() and hashCode() methods to the generated model
* classes. It demonstrates the process of adding methods to generated classes
*
* <p>The <code>equals</code> method generated by this class is correct in most cases,
* but will probably NOT be correct if you have specified a rootClass - because
* our equals method only checks the fields it knows about.
*
* <p>Similarly, the <code>hashCode</code> method generated by this class only relies
* on fields it knows about. Anything you add, or fields in a super class will
* not be factored into the hash code.
*
* @author Jeff Butler
*
*/
public class EqualsHashCodePlugin extends PluginAdapter {
private boolean useEqualsHashCodeFromRoot;
@Override
public void setProperties(Properties properties) {
super.setProperties(properties);
useEqualsHashCodeFromRoot = isTrue(properties.getProperty("useEqualsHashCodeFromRoot")); //$NON-NLS-1$
}
/**
* This plugin is always valid - no properties are required.
*/
@Override
public boolean validate(List<String> warnings) {
return true;
}
@Override
public boolean modelBaseRecordClassGenerated(TopLevelClass topLevelClass,
IntrospectedTable introspectedTable) {
List<IntrospectedColumn> columns;
if (introspectedTable.getRules().generateRecordWithBLOBsClass()) {
columns = introspectedTable.getNonBLOBColumns();
} else {
columns = introspectedTable.getAllColumns();
}
generateEquals(topLevelClass, columns, introspectedTable);
generateHashCode(topLevelClass, columns, introspectedTable);
return true;
}
@Override
public boolean modelPrimaryKeyClassGenerated(TopLevelClass topLevelClass,
IntrospectedTable introspectedTable) {
generateEquals(topLevelClass, introspectedTable.getPrimaryKeyColumns(),
introspectedTable);
generateHashCode(topLevelClass, introspectedTable
.getPrimaryKeyColumns(), introspectedTable);
return true;
}
@Override
public boolean modelRecordWithBLOBsClassGenerated(
TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {
generateEquals(topLevelClass, introspectedTable.getAllColumns(),
introspectedTable);
generateHashCode(topLevelClass, introspectedTable.getAllColumns(),
introspectedTable);
return true;
}
/**
* Generates an <code>equals</code> method that does a comparison of all fields.
*
* <p>The generated <code>equals</code> method will be correct unless:
*
* <ul>
* <li>Other fields have been added to the generated classes</li>
* <li>A <code>rootClass</code> is specified that holds state</li>
* </ul>
*
* @param topLevelClass
* the class to which the method will be added
* @param introspectedColumns
* column definitions of this class and any superclass of this
* class
* @param introspectedTable
* the table corresponding to this class
*/
protected void generateEquals(TopLevelClass topLevelClass,
List<IntrospectedColumn> introspectedColumns,
IntrospectedTable introspectedTable) {
Method method = new Method("equals"); //$NON-NLS-1$
method.setVisibility(JavaVisibility.PUBLIC);
method.setReturnType(FullyQualifiedJavaType
.getBooleanPrimitiveInstance());
method.addParameter(new Parameter(FullyQualifiedJavaType
.getObjectInstance(), "that")); //$NON-NLS-1$
method.addAnnotation("@Override"); //$NON-NLS-1$
commentGenerator.addGeneralMethodAnnotation(method, introspectedTable, topLevelClass.getImportedTypes());
method.addBodyLine("if (this == that) {"); //$NON-NLS-1$
method.addBodyLine("return true;"); //$NON-NLS-1$
method.addBodyLine("}"); //$NON-NLS-1$
method.addBodyLine("if (that == null) {"); //$NON-NLS-1$
method.addBodyLine("return false;"); //$NON-NLS-1$
method.addBodyLine("}"); //$NON-NLS-1$
method.addBodyLine("if (getClass() != that.getClass()) {"); //$NON-NLS-1$
method.addBodyLine("return false;"); //$NON-NLS-1$
method.addBodyLine("}"); //$NON-NLS-1$
StringBuilder sb = new StringBuilder();
sb.append(topLevelClass.getType().getShortName());
sb.append(" other = ("); //$NON-NLS-1$
sb.append(topLevelClass.getType().getShortName());
sb.append(") that;"); //$NON-NLS-1$
method.addBodyLine(sb.toString());
if (useEqualsHashCodeFromRoot && topLevelClass.getSuperClass().isPresent()) {
method.addBodyLine("if (!super.equals(other)) {"); //$NON-NLS-1$
method.addBodyLine("return false;"); //$NON-NLS-1$
method.addBodyLine("}"); //$NON-NLS-1$
}
boolean first = true;
Iterator<IntrospectedColumn> iter = introspectedColumns.iterator();
while (iter.hasNext()) {
IntrospectedColumn introspectedColumn = iter.next();
sb.setLength(0);
if (first) {
sb.append("return ("); //$NON-NLS-1$
first = false;
} else {
OutputUtilities.javaIndent(sb, 1);
sb.append("&& ("); //$NON-NLS-1$
}
String getterMethod = getGetterMethodName(
introspectedColumn.getJavaProperty(), introspectedColumn
.getFullyQualifiedJavaType());
if (introspectedColumn.getFullyQualifiedJavaType().isPrimitive()) {
sb.append("this."); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("() == "); //$NON-NLS-1$
sb.append("other."); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("())"); //$NON-NLS-1$
} else if (introspectedColumn.getFullyQualifiedJavaType().isArray()) {
topLevelClass.addImportedType("java.util.Arrays"); //$NON-NLS-1$
sb.append("Arrays.equals(this."); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("(), "); //$NON-NLS-1$
sb.append("other."); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("()))"); //$NON-NLS-1$
} else {
sb.append("this."); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("() == null ? other."); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("() == null : this."); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("().equals(other."); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("()))"); //$NON-NLS-1$
}
if (!iter.hasNext()) {
sb.append(';');
}
method.addBodyLine(sb.toString());
}
topLevelClass.addMethod(method);
}
/**
* Generates a <code>hashCode</code> method that includes all fields.
*
* <p>Note that this implementation is based on the eclipse foundation hashCode
* generator.
*
* @param topLevelClass
* the class to which the method will be added
* @param introspectedColumns
* column definitions of this class and any superclass of this
* class
* @param introspectedTable
* the table corresponding to this class
*/
protected void generateHashCode(TopLevelClass topLevelClass,
List<IntrospectedColumn> introspectedColumns,
IntrospectedTable introspectedTable) {
Method method = new Method("hashCode"); //$NON-NLS-1$
method.setVisibility(JavaVisibility.PUBLIC);
method.setReturnType(FullyQualifiedJavaType.getIntInstance());
method.addAnnotation("@Override"); //$NON-NLS-1$
commentGenerator.addGeneralMethodAnnotation(method, introspectedTable, topLevelClass.getImportedTypes());
method.addBodyLine("final int prime = 31;"); //$NON-NLS-1$
method.addBodyLine("int result = 1;"); //$NON-NLS-1$
if (useEqualsHashCodeFromRoot && topLevelClass.getSuperClass().isPresent()) {
method.addBodyLine("result = prime * result + super.hashCode();"); //$NON-NLS-1$
}
StringBuilder sb = new StringBuilder();
boolean hasTemp = false;
for (IntrospectedColumn introspectedColumn : introspectedColumns) {
FullyQualifiedJavaType fqjt = introspectedColumn.getFullyQualifiedJavaType();
String getterMethod = getGetterMethodName(introspectedColumn.getJavaProperty(), fqjt);
sb.setLength(0);
if (fqjt.isPrimitive()) {
switch (fqjt.getFullyQualifiedName()) {
case "boolean": //$NON-NLS-1$
sb.append("result = prime * result + ("); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("() ? 1231 : 1237);"); //$NON-NLS-1$
method.addBodyLine(sb.toString());
break;
case "byte", "char", "int", "short": //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
sb.append("result = prime * result + "); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("();"); //$NON-NLS-1$
method.addBodyLine(sb.toString());
break;
case "double": //$NON-NLS-1$
if (!hasTemp) {
method.addBodyLine("long temp;"); //$NON-NLS-1$
hasTemp = true;
}
sb.append("temp = Double.doubleToLongBits("); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("());"); //$NON-NLS-1$
method.addBodyLine(sb.toString());
method.addBodyLine("result = prime * result + (int) (temp ^ (temp >>> 32));"); //$NON-NLS-1$
break;
case "float": //$NON-NLS-1$
sb.append("result = prime * result + Float.floatToIntBits("); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("());"); //$NON-NLS-1$
method.addBodyLine(sb.toString());
break;
case "long": //$NON-NLS-1$
sb.append("result = prime * result + (int) ("); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("() ^ ("); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("() >>> 32));"); //$NON-NLS-1$
method.addBodyLine(sb.toString());
break;
default:
// all bases are covered above
break;
}
} else if (fqjt.isArray()) {
// Arrays is already imported by the generateEquals method, we don't need
// to do it again
sb.append("result = prime * result + (Arrays.hashCode("); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("()));"); //$NON-NLS-1$
method.addBodyLine(sb.toString());
} else {
sb.append("result = prime * result + (("); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("() == null) ? 0 : "); //$NON-NLS-1$
sb.append(getterMethod);
sb.append("().hashCode());"); //$NON-NLS-1$
method.addBodyLine(sb.toString());
}
}
method.addBodyLine("return result;"); //$NON-NLS-1$
topLevelClass.addMethod(method);
}
}