http断点续传简单实现（java)

/* p}3` "L=  
**SiteFileFetch.java V@g v  
*/ [YP{%1*RM  
package NetFox; [GPCd@  
import java.io.*; y XKddD  
import java.net.*; CY*o"@-o5)  
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public class SiteFileFetch extends Thread { #i.,+Q  
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SiteInfoBean siteInfoBean = null; //文件信息Bean #}Yrxf  
long[] nStartPos; //开始位置 -#v1/L/=  
long[] nEndPos; //结束位置 {G0=A~  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 c<,LE@V  
long nFileLength; //文件长度 %&_^I*  
boolean bFirst = true; //是否第一次取文件 !zvjgDlZv  
boolean bStop = false; //停止标志 PtYG%/s  
File tmpFile; //文件下载的临时信息 .uVd'  
DataOutputStream output; //输出到文件的输出流 6I: 6+n  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） O/|))H?C  
public SiteFileFetch(SiteInfoBean bean) throws IOException U(0FL6sPC  
{ 7O'.KoMw  
siteInfoBean = bean; Q-<Qm?  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Ml$<x"Q  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 5D.Sg;\  
if(tmpFile.exists ()) j g//I<D  
{ e pp04~  
bFirst = false; 7*j!ZUzp  
read_nPos(); :_y!p  
} N2k<W?wQ  
else
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7  
{ V*ao@;sD  
nStartPos = new long[bean.getNSplitter()]; 76"4Q!  
nEndPos = new long[bean.getNSplitter()]; r<vy6  
} VP>*J`'H  
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} (:qc[,m  
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public void run() 5wmd[YL  
{ #GLW3}  
//获得文件长度 5?F5xiW  
//分割文件 t[J=8rhER  
//实例FileSplitterFetch oz>2P.7  
//启动FileSplitterFetch线程 M,S'4Szuk  
//等待子线程返回 $%q=tn'EX  
try{ nX 9]dz
 
if(bFirst) S\h5 D2G;  
{ v+"4YIN  
nFileLength = getFileSize(); w6Nnx5Ay  
if(nFileLength == -1) CxeW5qc  
{ `:Gzjngc  
System.err.println("File Length is not known!"); JC%&d
1  
} 4MS#`E7LrC  
else if(nFileLength == -2) 5LB{b]w7m  
{ Jn^b}bk t  
System.err.println("File is not access!"); Hc=QSP  
} C6[W/,eS  
else t+}
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{ Bp_R"DS7A  
for(int i=0;i<nStartPos.length;i++) 7]xDMu'^&f  
{ i
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); ^l|b>z"0ao  
} A $gn{ c  
for(int i=0;i<nEndPos.length-1;i++) 8'zZVX D<  
{ UL-_z++G  
nEndPos = nStartPos[i+1]; sa4w.9O1GS  
} *9"x0bth  
nEndPos[nEndPos.length-1] = nFileLength; s6@mXO:H^  
} HB8s[]A:D  
} l@Vv%w9H  
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//启动子线程 A$3Rb
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; IO)#O<  
for(int i=0;i<nStartPos.length;i++) m9oOH5@K~  
{ H:]cBk^[,  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), @2/|rq  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), OIL8'xY.w  
nStartPos,nEndPos,i); NDP" @  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [p9v#\G; [  
fileSplitterFetch.start(); W\k8f+Ke  
} ?:J_+?{E  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), VwE4:/7YN  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); HKXC=^}x'  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", +q}t%K5  
nEndPos = " + nFileLength); 8^>c_%e}  
// fileSplitterFetch[nPos.length-1].start(); lP3|h*  
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)Q'E^[Ua  
//等待子线程结束 bu|.Jw"  
//int count = 0; zo(#tQ-'m  
//是否结束while循环 6sSwSS
 
boolean breakWhile = false; <'~m1l#2  
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while(!bStop) ^iMr't\b  
{ WHY/x /$  
write_nPos(); L"|Bm{Run  
Utility.sleep(500); )pH
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breakWhile = true; 3NtUB;!  
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for(int i=0;i<nStartPos.length;i++) &)mZ~cPU3  
{ cdt9hH`Cd  
if(!fileSplitterFetch.bDownOver) l,7& z  
{ hc3hU  
breakWhile = false; ZOqS"3j! j  
break; }+9?)f{?@  
} KOS0Du  
} k0e}`#t  
if(breakWhile) %hsCB .r>|  
break; 'd+fGx7i  
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//count++; b$,Hlh,^  
//if(count>4) l~rj7f;  
// siteStop(); }_]AQN$'G  
} e{5?+6KH  
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System.err.println("文件下载结束！"); jr4xh{Z`  
} [34N/;5  
catch(Exception e){e.printStackTrace ();} JcR|{9ghT  
} xmv%O&0^}  
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//获得文件长度 :+,;5  
public long getFileSize() NS[eQ_rT  
{ %xg+UW }  
int nFileLength = -1; Plp.\N%f3  
try{ R@\}iyM  
URL url = new URL(siteInfoBean.getSSiteURL());  l(?B0  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _]`7et\=  
httpConnection.setRequestProperty("User-Agent","NetFox"); [s>3xWZ+a  
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?{S>%P A_B  
int responseCode=httpConnection.getResponseCode(); ,-#MEr  
if(responseCode>=400) mVZh_R=a  
{ !CGX\cvW  
processErrorCode(responseCode); u#@/^h;  
return -2; //-2 represent access is error W%!(kN&d  
} 8wsU`40=Q  
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String sHeader; fwFJe(.  
5?k5J\+  
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for(int i=1;;i++) I\.|\^  
{ DXLXGvcM  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); :<qe2Z5k  
//Utility.log(in.readLine()); *,\"}x*  
sHeader=httpConnection.getHeaderFieldKey(i); ?G,4N<]Nu  
if(sHeader!=null) >!=@TK(~  
{ c@t?R$c  
if(sHeader.equals("Content-Length")) ^c\O,*:  
{ $+*nb4  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); |Kd#pYt%O  
break; f$o^Xu  
} 5*YoK)2J  
} |p6d]#z3  
else aOzIo-  
break; iS$[dC ?N  
} >2s4BV[(  
} G?W:O{n3  
catch(IOException e){e.printStackTrace ();} Rd#R}yA  
catch(Exception e){e.printStackTrace ();} Y!<m8\  
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Utility.log(nFileLength); +F;2FD$  
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return nFileLength; v~nKO?{   
} E\[BE<y  
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*G58t`]r  
//保存下载信息（文件指针位置） ${ {4L?7  
private void write_nPos() f7=MgFi  
{ YN8x|DLi?  
try{ tIuM9D{P  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 8Qg10Yjy  
output.writeInt(nStartPos.length); ]cpb;UfM  
for(int i=0;i<nStartPos.length;i++) Z=JKBoAY  
{ /Q1*Vh4  
// output.writeLong(nPos); 5)#j}`6  
output.writeLong(fileSplitterFetch.nStartPos); %B%_[<B  
output.writeLong(fileSplitterFetch.nEndPos); 46:<[0Psl/  
} uH[WlZ4  
output.close(); aCG rS{  
} 0?7yM:!l  
catch(IOException e){e.printStackTrace ();} PIri|ZS  
catch(Exception e){e.printStackTrace ();} C >*z^6Gz  
} `OfhzO
p  
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//读取保存的下载信息（文件指针位置） b"I#\;Ym  
private void read_nPos() fs!dI  
{ h.\I tK{)  
try{ \"
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); c!H
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int nCount = input.readInt(); P6gkbtg  
nStartPos = new long[nCount]; ]rG=\>U3~  
nEndPos = new long[nCount]; R]"Zv'M(AM  
for(int i=0;i<nStartPos.length;i++) )d3 09O  
{ xs"i_se  
nStartPos = input.readLong(); Z0<Vss  
nEndPos = input.readLong(); N^;lp<{6?  
} >dAl*T  
input.close(); {<-s&%/r  
} :\;9y3  
catch(IOException e){e.printStackTrace ();} &f.5:u%{b  
catch(Exception e){e.printStackTrace ();} zIc6L3w$  
} DsdM:u*s  
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private void processErrorCode(int nErrorCode) P27Ot1px  
{ k\OZ'dS  
System.err.println("Error Code : " + nErrorCode); JU8}TX  
} Za@\=}Tt  
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//停止文件下载 Q
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public void siteStop() KMhrw s{&B  
{ s\*p|vc  
bStop = true; $xu2ZBK  
for(int i=0;i<nStartPos.length;i++) Zo=,!@q(  
fileSplitterFetch.splitterStop(); Ab$E@H#  
)q$[uS_1[  
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} D^r g-E[L  
} +Nn >*sz  
//负责部分文件的抓取 >@N.jw>#T  
**FileSplitterFetch.java `gl?y;xC  
*/ yCjc5d|tT  
package NetFox; %pZT3dcK  
"@x(2(Y&  
+wQ5m8E  
import java.io.*; Ec7xwPk  
import java.net.*; A+/Lt>+AS  
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public class FileSplitterFetch extends Thread { r'i99~  
]D6<6OB  
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String sURL; //File URL 7] y3<t  
long nStartPos; //File Snippet Start Position 'M%iS4b{IM  
long nEndPos; //File Snippet End Position '&CZ%&(Gw  
int nThreadID; //Thread's ID 'bfxQ76@sa  
boolean bDownOver = false; //Downing is over h),;j`PrC  
boolean bStop = false; //Stop identical IsE&k2 SD  
FileAccessI fileAccessI = null; //File Access interface ~criZI/  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException r,eH7&P9{  
{ c<1$zQY!  
this.sURL = sURL; [)`*k#.=  
this.nStartPos = nStart; rbf5~sw&8+  
this.nEndPos = nEnd; 3r%v@8)!b  
nThreadID = id; 9No6\{[M  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 n
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} Yte*$cJ=  
( %sfwv  
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public void run() MKtI3vi?  
{ 51}C`j|V3{  
while(nStartPos < nEndPos && !bStop) *42KLns  
{ `
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try{ HtN:v  
URL url = new URL(sURL); @Hj]yb5  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |(~IfSE2  
httpConnection.setRequestProperty("User-Agent","NetFox"); r%: :q^b3  
String sProperty = "bytes="+nStartPos+"-"; Xp;'Wa"@  
httpConnection.setRequestProperty("RANGE",sProperty);  5+GTK)D  
Utility.log(sProperty); @!$xSH  
2-S}#S}2C  
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InputStream input = httpConnection.getInputStream(); S> Fb'rJ3  
//logResponseHead(httpConnection); IlEU6Rs  
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byte[] b = new byte[1024]; KMT$/I{p,  
int nRead; uJ"#j X  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) drCL7.j#L  
{ %~eu&\os  
nStartPos += fileAccessI.write(b,0,nRead); o5],c9R9b  
//if(nThreadID == 1) ~,W|i  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 1sUgjyGQ  
} .WglLUJ:Z  
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"P5,p"k:)  
Utility.log("Thread " + nThreadID + " is over!"); :Nz TEK  
bDownOver = true; %m|BXyf]_B  
//nPos = fileAccessI.write (b,0,nRead); B{#Fm6  
}  ^Oj^7.T+  
catch(Exception e){e.printStackTrace ();} ZrYRLg  
} /p-k'387  
} @V4nc 'o.  
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*h?*RUQ  
//打印回应的头信息 Sn97DCdk  
public void logResponseHead(HttpURLConnection con) B4OFhtYE  
{ }T%E;m-  
for(int i=1;;i++) 1%@i4  
{ gC6Gm':c  
String header=con.getHeaderFieldKey(i); ~Q- /O~  
if(header!=null) i&HU7mP/  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); W__$ i<1  
Utility.log(header+" : "+con.getHeaderField(header)); UeUOGf ,  
else Na\&}GSf^  
break; jcePSps]  
} Jcvp<  
} $hM9{  
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public void splitterStop() x}C$/7^  
{ (>Sy,  
bStop = true; 1\jj3Y'i'  
} I/h(*~/  
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} 3&X5*-U  
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/* ziAn9/sT  
**FileAccess.java P@etT8|V  
*//文件访问(定位，写) V2Z
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package NetFox; d.snD)X  
import java.io.*; a/d8_(0  
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public class FileAccessI implements Serializable{ p=Qo92 NH  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 *XXa
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RandomAccessFile oSavedFile; B)DtJf  
long nPos; w
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public FileAccessI() throws IOException O|;|7f
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{ 6%VRQ#g!  
this("",0); ]xJ2;{JWsO  
} e~G IUwJ  
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public FileAccessI(String sName,long nPos) throws IOException B3u:D"
t  
{ q_6<}2m,U  
oSavedFile = new RandomAccessFile(sName,"rw"); 0@!-+}i  
this.nPos = nPos; =rNI&K_<  
oSavedFile.seek(nPos); S?H qrf7<  
} }e1]Ib!  
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public synchronized int write(byte[] b,int nStart,int nLen) EU7mP MxJ  
{ ]T<RC\o  
int n = -1; :as2fO$?  
try{ gdBH\K(\  
oSavedFile.write(b,nStart,nLen); a '<B0'  
n = nLen; ][Cg8  
} cj3P]2B#  
catch(IOException e) 7baQ4QY?n  
{ y#{> tC  
e.printStackTrace (); LZpqv~av  
} 
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return n; p\|*ff0  
} LwCf}4u"  
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} ;x=0+0JD  
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/* \N]2V(v  
**SiteInfoBean.java Xpf:I  
*/ X04JQLhy"  
package NetFox; z`@|v~i0`  
&q[`lIV,L  
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public class SiteInfoBean { NHzhGg]  
IsiCHtY9  
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private String sSiteURL; //Site's URL &p^8zEs  
private String sFilePath; //Saved File's Path .\ces2,  
private String sFileName; //Saved File's Name @X>Oj.  
private int nSplitter; //Count of Splited Downloading File <bOi}  
$~.'Tnk)  
>BlF< d`X  
public SiteInfoBean() n|I5ylt  
{//nSplitter的缺省值为5 }7|UA%xz  
//default value of nSplitter is 5 lxD~[e  
this("","","",5); LZ*ZXFIg  
} 64-;| k4F  
p#(5 ;  
nJo6;_MI!  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Ut^ {4_EC  
{ V> @+&q  
sSiteURL= sURL;  HO =\  
sFilePath = sPath; 4Q(GX.5  
sFileName = sName; .q(1  
this.nSplitter = nSpiltter; D~JrO]mi  
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5"9!kZ(<  
} },G5!3  
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public String getSSiteURL() &,~Oi(SX5  
{ aRF}FE,u  
return sSiteURL; p{4nWeH?B  
} p!3!&{  
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?Q%X,!~\:  
public void setSSiteURL(String value) 0T7""^'&  
{ 1|Z!8:&pj  
sSiteURL = value; .:=G=v=1  
} .+ g8zbD4  
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public String getSFilePath() LL^WeD_Y  
{ .a`(?pPr,  
return sFilePath; aqzIMOAf  
} aaM76;  
f& >[$zh  
8!(09gW'>  
public void setSFilePath(String value) K_sHZ  
{ "xKykSk  
sFilePath = value; ?B~S4:9  
} gG6j>%y  
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=;?afUj  
public String getSFileName() (7_}UT@w-  
{ 3c.,T  
return sFileName; aaODj>  
} V1Opp8  
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public void setSFileName(String value) TY6Q;BTU  
{ ?m>!P@ M  
sFileName = value; [=q&5'FY0  
} ^J-\s_)"  
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U^.kp#x#  
public int getNSplitter() (TJ )Y7E  
{ dGY:?mf&  
return nSplitter; !O}^Y  
} a08`h.dyN  
V 0M&D,  
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public void setNSplitter(int nCount) VuWBWb?0Q  
{ R+y 9JE  
nSplitter = nCount; )D"E]  
} <UC_QPA\  
} {WoS&eL  
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/* KJ;;825?  
**Utility.java 4V9S~^v|  
*/ 5:sk&0:@U  
package NetFox; $)6%LG_@  
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public class Utility { E+!A0!1  
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public Utility() Qt`;+N(  
{ Ods/1 KW  
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} yrVk$k#6}  
+zf[Im%E  
//线程睡眠 GLE/ 1  
public static void sleep(int nSecond) 7`_`V&3s  
{ :[C"}mR1  
try{ o!-kwtw`l  
Thread.sleep(nSecond); cA8A^Iv:0  
} +9!=pRq  
catch(Exception e) 'NYW`,  
{ U1^3 &N8  
e.printStackTrace (); 6I!B>V#U+  
} g/f^|:  
} p]E\!/  
'BOMFp7c  
//日志 bc}BQ|Q  
public static void log(String sMsg) 2Mo oqJp  
{ <tx`#,  
System.err.println(sMsg); *'ffMnSZ  
} wXKg^%t\  
k ^(RSu<  
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public static void log(int sMsg) sRkPXzK  
{ x=%wPVJ  
System.err.println(sMsg); tEFbL~n  
}
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} `ZhS=ezgr  
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/* UOYhz.  
**TestMethod.java V krjs0  
*/ eOUv#F  
package NetFox; ,?/AIL]_  
9T;DFUM  
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public class TestMethod { '74*-yd  
*)u%KYGr  
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public TestMethod() %
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{ ///xx/weblogic60b2_win.exe \;bDDTM  
try{ mP[ZlS~"  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); e61e|hoX\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); '?)<e^  
SiteFileFetch fileFetch = new SiteFileFetch(bean); :F`-<x/  
fileFetch.start(); c>.=;'2  
} `m+o^!SGe  
catch(Exception e){e.printStackTrace ();} P?/Mrz   
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} GX0S9s  
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:xy4JRcF  
public static void main(String[] args) i!u:]14>  
{ XkRPD  
new TestMethod(); YE;Tpji  
} h6~H5X  
} ZBsV  
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