io.ebean.bean.ToStringBuilder Maven / Gradle / Ivy
package io.ebean.bean;
import java.util.Collection;
import java.util.IdentityHashMap;
import java.util.Map;
/**
* Helps build toString content taking into account recursion.
*
* That is, it detects and handles the case where there are relationships that recurse
* and would otherwise become an infinite loop (e.g. bidirectional parent child).
*/
public final class ToStringBuilder {
/**
* The max number of objects that we allow before stopping content being appended.
*/
private static final int MAX = 100;
/**
* Max length of content in string form added for any given value.
*/
private static final int TRIM_LENGTH = 500;
/**
* The max total content after which we stop content being appended.
*/
private static final int MAX_TOTAL_CONTENT = 2000;
private final IdentityHashMap id = new IdentityHashMap<>();
private final StringBuilder sb = new StringBuilder(50);
private boolean first = true;
private int counter;
@Override
public String toString() {
return sb.toString();
}
/**
* Set of an object being added.
*/
public void start(Object bean) {
if (counter == 0) {
id.putIfAbsent(bean, 0);
}
if (counter <= MAX) {
sb.append(bean.getClass().getSimpleName()).append('@').append(counter).append('(');
}
}
/**
* Add a property as name value pair.
*/
public void add(String name, Object value) {
if (value != null && counter <= MAX) {
if (value instanceof BeanCollection) {
if (((BeanCollection)value).isReference()) {
// suppress unloaded bean collections
return;
}
}
key(name);
value(value);
}
}
/**
* Add raw content.
*/
public void addRaw(String content) {
sb.append(content);
}
/**
* End of an object.
*/
public void end() {
if (counter <= MAX) {
sb.append(')');
}
}
private void key(String name) {
if (counter > MAX) {
return;
}
if (first) {
first = false;
} else {
sb.append(", ");
}
sb.append(name).append(':');
}
private void value(Object value) {
if (counter > MAX) {
return;
}
if (value instanceof ToStringAware) {
if (value instanceof BeanCollection) {
((ToStringAware) value).toString(this);
} else if (push(value)) {
((ToStringAware) value).toString(this);
}
} else if (value instanceof Collection) {
addCollection((Collection) value);
} else if (value instanceof Map) {
addMap(((Map) value));
} else {
String content = String.valueOf(value);
if (content.length() > TRIM_LENGTH) {
content = content.substring(0, TRIM_LENGTH) + " (trimmed)";
}
sb.append(content);
if (sb.length() >= MAX_TOTAL_CONTENT) {
sb.append(" ...");
counter += MAX;
}
}
}
public void addMap(Map map) {
if (map == null || map.isEmpty()) {
sb.append("{}");
} else {
boolean firstElement = true;
sb.append('{');
for (Map.Entry entry : map.entrySet()) {
if (firstElement) {
firstElement = false;
} else {
sb.append(", ");
}
sb.append(entry.getKey()).append(':');
value(entry.getValue());
if (counter > MAX) {
return;
}
}
sb.append('}');
}
}
/**
* Add a collection of values.
*/
public void addCollection(Collection c) {
if (c == null || c.isEmpty()) {
sb.append("[]");
return;
}
boolean firstElement = true;
sb.append('[');
for (Object o : c) {
if (firstElement) {
firstElement = false;
} else {
sb.append(", ");
}
value(o);
if (counter > MAX) {
return;
}
}
sb.append(']');
}
private boolean push(Object bean) {
if (counter > MAX) {
return false;
}
if (counter == MAX) {
sb.append(" ...");
counter++;
return false;
}
Integer idx = id.putIfAbsent(bean, counter++);
if (idx != null) {
--counter;
sb.append(bean.getClass().getSimpleName()).append('@').append(idx);
return false;
}
first = true;
return true;
}
}